- Email: [email protected]
The effects of AlN on secondary recrystallization textures in cold rolled and annealed (001)[100] single crystals of 3% silicon iron
THE EFFECTS OF AlN ON SECONDARY IN COLD ROLLED AND ANNEALED 3%
RECRYSTALLIZATION TEXTURES (OOl)[lOO] SINGLE CRYSTALS OF
SILICON
S. TAGUCHIt
IRON*
and A. SAKAKURAT
A study ~8s made of the effects of AlN on the recrystallization textures in cold rolled and annealed (OOl)[lOO] crystals of 3 % silicon iron and AlN w&s found to have 8 great effect on secondary recrystallizrttion textures. The influence of cold rolling reduction w8s investigated 8s well. The following 8re the results of these investigations. Cold rolled and annealed (OOl)[lOO] single crystals containing fine needle-like AlN about 1 p or under in length develop (OOl)[lOO] oriented secondary recrystallization textures at the expense of 8 quadruplet {113}(301) oriented primary recrystallized matrix, while those contrtining no AlN produce normal grain growth textures of primary recrystallized matrix. The crystal structure of AlN is hexagonal close packed, with a = 3.104 & c = 4.965 A, and the needle-like AIN forms on {IOO} x or {120}= planes of silicon iron with the orien’ation relationships of or
{lO.l)AlN
/I {120)1
{124AlN
11{]=}a
The mechanism of secondary recrystallization is expleined by the concept of “preferred orientation inhibition” which is derived from the above-mentioned relationships between AlN and silicon iron.
EFFETS
DE AIN SUR LES MONOCRISTAUX
TEXTURES DE RECRISTALLISATION (OOl)[lOO] DE Fe-3% Si LAMINES ET
SECONDAIRE RECUITS
DE
Les auteurs ont Btudii?les effets de AlN sur les textures de recristallisation des monocristaux (001) [loo] de Fe-3 ‘A Si lamin& et recuits. Le nitrure d’aluminium 8 un effet important sur les textures de recristallisation secondaire. L’influence du pourcentage de reduction lors du laminege 8 BtB aussi envisagke. Les monocristaux (001) [loo] lamin& et recuits qui contiennent des aiguilles de nitrures d’aluminium de l’ordre de 1 micron ou moins, presentent des textures de recristallisation secondaire orient&es influencees par l’orientation de recristallisation prim8ire de 18 metrice et qui est {I 13) (301). Les cristaux qui ne contiennent pas de nitrures d’aluminium prbsentent des textures de croissance normales de la matrice recristrtlli&e. La structure cristalline du nitrure d’aluminium est hexagonale avec a = 3,104 il, c = 4,965 A. Les aiguilles de nitrure se ferment sur les plans {lOO}a et {120}a du Fe-Si avec les relations d’orientations suivantes: {IO,IJA~N I/{120)~ {1%2}AlN
11{122}a
Le m&anisme de recristallisation secondaire est enfin interpret& sur 18base du concept de “l’inhibition des orientations pr6f&entielles” qui d&oule des reletions d’orientation mention&es et existant entre le nitrure et le fer-silicium.
DER EINFLUB VON AlN AUF DIE SEKUNDliREN REKRISTALLISATIONSTEXTUREN IN KALT GEWALZTEN UND ANGELASSENEN (001) [loo]-3% EISENEINKRISTALLEN
Si-
Es wurde der EinfluD van AIN auf die Rekristallisationstexturen in kalt gewalzten und angelassenen (001) [loo]-Kristallen 8us 3 % Si-Eisen untersucht. Diese Untersuchungen brachten die folgenden Ergebnisse. Kalt gewelzte und angelassene (001) [loo]-Einkristalle mit feinem nadeliihnlichem AIN van 1 p oder weniger L&nge entwickeln (001) [ lOO]-orientierte sekundare Rekristallisationstexturen euf Kosten einer Quadruplet-{1 13) (301)-orientierten prim&r rekristallisierten Matrix. Die Kristallstruktur von AIN ist hexagonal dichtest gepaokt, mit a = 3,104 A, c = 4,965 A. Das nadelfijrmige ALN bildet sich auf { 10O}r~-oder { 120}a-Ebenen van Siliziumeisen, mit den Orientierungsbeziehungen {lO,l)~i~
oder
jl (120)~
{12,2}AlN 1) {122)a. Der Mechanismus der sekundiiren Rekristallisation wird erkliirt mit der Vorstellung einer “bevorzugten Orientierungsbehinderung”, welche van den obigen Beziehungen zwischen AlN und Siliziumeisen hergeleitet wird.
* Received February 2, 1965; revised Mey 11, 1965. t Technical Research Institute, Y&w&t8 Iron 8nd Steel Co., Ltd, Kitakyushu-Shi, ACTA
METALLURGICA,
VOL.
14, MARCH
1966
405
Japan.
406
ACTA
METALLURGICA,
VOL.
14,
1966
INTRODUCTION
in diameter which were prepared by the authors’ method,c4) i.e. cross rolling and annealing of comHeretofore numerous studies have been made concerning cold rolled 3 y0 silicon iron crystals initially mercial grade hot rolled 3 ‘A silicon iron sheets near (OOl)[lOO] and its recrystallization textures. containing a small amount of Al. In the final annealWalter and Hibbardo) reported that after 66% ing of this preparing process, the sheets were held for reduction by rolling the texture was noticed to be 20 hr at 1200°C and cooled at the rate of lOO”C/hr in consisting of the two symmetrical bands having such N50 gas:. The crystals with (001) plane within 5’ of orientations as were brought about by rotating the the plane of the sheets were selected and cut from the (OOl)[lOO] oriented crystal about 30” clockwise and sheets. These crystals were then subjected to pre-heat counter-clockwise about the normal of the rolling treats in order to change content, size and distribution plane, aud the annealed texture was near (OOl)[lOO]. of AlN. Tables 1, 2 and 3 summarize the conditions Walter and Kocht2) observed by transmission electron of pre-heat treats and the chemical analysis after microscopy the cold rolled textures and recrystallizatreats. These starting crystals were cold rolled with the reduction in thickness of 30, 50, 70, 80 and 87.5 % tion behavior of (OOl)[lOO] oriented high purity 3% silicon iron crystals. According to these authors, the respectively in the [lOO] direction. These cold rolled two sets of symmetrical deformation bands and crystals were heated at the rate of lOO’C/hr, annealed transition bands were formed when crystals were at 1200°C for 20 hr and cooled at the rate of lOO”C/hr. rolled. Hut3) reported that some of the orientation The gas used was cracked ammonia in heating and of recrystallized grain formed within the transition hydrogen in holding and cooling. band was (113) with the direction of rolling inclined Fine grained specimens were thinned to 0.05 mm about 17” to the [liO] direction. in thickness and placed in an integrating specimen The present authors noticed the effect of AlN on holder and the texture was determined by transmission recrystallization textures, especially on secondary X-ray method using MO-K, radiation. Large seconrecrystallization textures of 3 y0 silicon iron single dary grains and growth grains were etched by a special crystals initially (OOl)[lOO] oriented. The aim of the chemical solution, i.e. the solution of ferrous sulphate, present study is (firstly) to determine the relation sulphuric acid and water, and the texture was debetween recrystallization textures and AlN contained termined by optical goniometer. The chemical analysis in crystals, and (secondary) to clarify the characof AlN was carried out by the bromine-methyl acetate teristics of AlN which are of effect to develop seconmethod. Observation of precipitated AlN was made dary recrystallization textures, and (lastly) to discuss by transmission electron microscopy using carbon the mechanism of secondary recrystallization. extraction replica, and suitable foils were cut for examination by transmission electron microscopy EXPERIMENTAL PROCEDURE and electron diffraction pattern The single crystals used in this study were commercial purity 3% silicon iron with the (OOl)[lOO] $ N50 and N75 gas means N,50 volume o/0 + H,50 volume orientation. The crystals were chosen from the sheets % and N,75 volume % + Hz25 volume % mixture gas reconsisting of grains 1 mm in thickness and 50-100 mm spectively. TABLE 1. The relation between recrystallization textures and the conditions of pre-heat treat I
Crystal
Temp. (“C)
Time (hr)
Gas
Cooling rate (“Wr)
None
OA
Recrystallization textures ( %)
Chemical analysis of crystals (wt. %)
Conditions of preheat treat C
Si
acid sol. Al
total N
N as AlN
0.007
2.95
0.019
0.0142
0.010
2.89 2.92
0.018
0.0086
0.0128 -~ 0.0072 63 54
SC
PC
SC
90
5
5
90 50 90 40 5
N50
100
::
za
100
7 6”
2.90 2.91
18 ::
1250
20
N;O
100
4
2.85
21
6”: 89 59
;:
1200
::
H H:
100
0.0061
0.0126
0.0012 10
0.0001 1
0 0
::
vo
1200
20
Vat. *
100
0.006
0.028
0.0004
0.0001
5
90
;::
1200
:;
1200
5A
* Vat. means vacuum.
2.81
z:
4: 5 :8
1: 2; 6
5
TAGUCHI
FIG.
AND
SAKAKURA:
EFFECT
OF AIN ON Si-Fe
407
SC and SG textures PC texture 1. Macrostructuresof the annealedcrystalsshowing3 typical textures.
EXPERIMENTAL RESULTS 1. The pre-heat treats of crystals and recryst&zation textures Starting single crystals subjected to the pre-heat treat which is shown in Table 1 were rolled 70 “/o in the direction of [loo], then annealed. The relation between recrystallization textures and the conditions of pre-heat treat is shown in the last column of this table. Here, “SC” means the (OOl)[lOO] oriented secondary recrystallization texture consisting of grains with diameter of 10-100 mm, “PC” the quadruplet {113)(301) oriented normal grain growth texture of primary recrystallized matrix which is related by approximately 25-30’ rotations about two (110) axes of the (OOl)[lOO] orientation, and “SG” the doublet {011}(100) oriented secondary recrystallization texture. The macrostructures and the (100) pole figure of these 3 textures are shown in Figs. 1 and 2. Table 1 shows that in specimens OA, 1A and 3A containing some amount of AlN, “SC” textures develop, on the other hand, in specimens 10, 20 and VO containing little or no AlN, “PC” textures are found. But we must notice that although specimens 2A and 4A, which were subjected to pre-heat treat for a long time, contain AlN, their ‘SC” textures are rather poor ; especially in specimen 5A held for 20 hr at 125O”C, almost no “SC” texture From these results, it appears that the develops.
development of the (OOl)[lOO] oriented secondary recrystallization texture is dependent not only upon the quantity of AlN but also upon the precipitation size and distribution of AlN. Now starting single crystals were subjected to the pre-heat treat shown in Table 2: held in N, gas at 12OO”C,quenched or slow cooled, then cold rolled 70 %
.)9
,’
/
3
:z
\.\
FIG.2. [loo] pole figureof annealedcrystals.
408
ACTA TABLE
METALLURGICA,
Recrystallization textures ( %)
acid sol. Al
total N
SC
PC
SG
quench quench quench quench quench
0.021 18 22 25 25
0.0131 136 149 130 127
0.0081 89 92 78 63
5 5 5 5 5
90 90 90 90 90
5 5 5 5 5
N* N*
water quench water quench
24 16
82 81
29 1
5 5
90 90
5 5
N, N* N, N, N, N, N,
100 100 100 100 100 100 100
0.021 19 22 17 17 17 11
0.0138 139 148 125 114 97 82
0.0114 118 115 102 89 56 60
90 90 90 90 70 40 50
5 5 5 5 25 55 45
5 5 5 5 5 5 5
Cooling rate (“C/hr)
Time (hr)
Gas
AS 32 33 34 35 36
1200 1200 1200 1200 1200
l/12 1 5 10 20
N* N, N, N* N*
water water water water water
37 38
1200 1200
40 60
AS 42 43 44 45 46 47 48
1200 1200 1200 1200 1200 1200 1200
l/12 1 5 10 20 40 60
Zl?
3. The relation between recrystallization textures and the conditions of pre-heat treat III Chemical analysis of crystals (wt. %)
Conditions of pre-heat treat Crystal
AS 101 102 103 104 105 106
1966
Chemical analysis of crystal (wt. %)
Temp. (“C)
TABLE
14,
2. The relation between recrystallization textures and the conditions of pm-heat treat II
Conditions of pre-heat treat Crystal
VOL.
Recrystallization textures ( “/,)
Temp. (“C)
Time (hr)
Temp. of quench (“C)
Holding time (hr)
Cooling rate
acid sol. Al
N as N
N as AlN
SC
PC
SG
1300 1300 1300 1300 1300 1300
l/6 l/6 l/6 l/6 l/6 l/6
0 400 600 800 1000 1200
l/2 l/2 l/2 l/2 l/2
water quench water quench water quench water quench water quench
0.022 23 22 30 24 24
0.0098 74 94 88 92 97
0.0020 30 48 68 81 62
0 0 5 40 40 0
100 100 90 40 40 100
0 0 5 20 20 0
and annealed. The recrystallization textures were shown in the last column of this table. From these results, it is clear that even if the quantity of AlN is large, “SC” texture does not develop in the crystals quenched from the pre-heat temperature, and AlN effective for the development of “SC” texture appears to be line precipitates that may precipitate during slow cooling and is estimated to be from 0.0033 (= 0.0114-0.0081) to 0.0023 (= 0.0115-0.0092) wt. % N as AlN in quantity. And it seems that the chemical analysis value of N as AlN is attributed largely to the agglomerated AlN that is not in solution during the pre-heat treat. Starting single crystals were finally subjected to the pre-heat treat shown in Table 3: held for 10 min in N75 gas at the temperature of 1300°C so high that AlN may be in solution, quenched to the temperatures of O”, 400”, 600°, 800”, 1000’ and 1200% respectively and held at these temperatures for 30 min and then water quenched. AlN is reprecipitated by holding at these temperatures. From the recrystallization textures of crystals pre-heat treated, cold rolled 70 %
and annealed, it is clear that AlN effective for the development of “SC” texture precipitates in the range 8oo”c-1OOo”c. 2. Cold rolled, primary and secondary recrystallization textures in cold rolled (OOl)[lOO] oriented single crystals When rolled 70x, (OOl)[lOO] oriented single crystals reorient to form deformation bands (band B, and B, hereinafter) that are 0.01-0.1 mm in width and related by 26” rotations clockwise and counterclockwise about the normal of the (001) plane, as shown in Fig. 3. Figure 4 gives a stereogram of (110) poles of the cold rolled crystal OA. As shown in Fig. 4, the cold rolled texture consists mainly of a doublet {001}(210) orientation marked by black and white circles. Figure 5 gives electron micrographs showing the transition band structure which is the region between band B, and B,. Figure 5(a) shows C-band characterized by approximately (OOl)[lOO] orientation or near and Fig. 5(b) shows M-band approximately (113}(301) orientation or near. They are found to be
TAGUCHI
AND
SAKAKURA:
EFFECT
OF AlN
ON Si-Fe
409
bold rolling direction Fra.
3. Macroetched surf&e of (OOl)[lOO] crystal OA rolled 70 %. x 240
minor components of the cold rolled texture, marked by cross, black and white squares and triangles in Fig. 4. Furthermore, the existence of primaries having (OOl)[lOO] orientation and a quadruplet {113}(301) orientation was recognized as shown in Fig. 9 described later. They are designated C- and M-primaries. Then it would appear that minor components of cold rolled textures act as nuclei of primary recrystallization. M-band with a quadruplet (113)(301) orientation is related by approximately 25-30” rotations about two (110) axes of the (OOl)[lOO] oriented crystal. Here, the rotations about [ilO], i.e. M, and Ms, and about [iiO], i.e. Ms and M4 are distinguished. When heated at the rate of lOO”C/hr, primary grains begin to originate within the transition bands, as shown in Fig. 6, at the temperature of 550°C and primary recrystallization completes at 670°C and 710°C in crystal OA and VO respectively. When the temperature is increased, C oriented secondaries begin to grow at 800°C and complete at 1100°C in crystal OA, while the normal grain growth of M oriented primaries occurs in crystal VO. Figure 7 shows the grain size as a function of annealing temperature in the crystals OA, 2A and VO. It must be noticed that the matrix grain size appears independent of annealing temperature from 800°C to 1000°C in the crystal OA. Figures 8 and 9 give the micro-structure and texture of primary recrystallized matrix obtained from the crystal OA rolled 70% and heated up to 900°C at the rate of lOO”C/hr. The texture consists mainly of a
FIG. 4. (110) pole figure of crystals OA cold rolled 70 %. IX: random intensity.
quadruplet { 113}(301) orientation. The same results are also obtained in the crystal VO . These orientations are in good agreement with the orientations of “PC” texture shown in Fig. 2. Thus it is proved that the “PC” texture is normal grain growth texture of M oriented primary recrystallized matrix, while “SC” texture is produced by the growth of C oriented secondaries. 3. The inJEuenceof cold rolling reduction on the development of “SC” texture When the crystal OA is rolled with the reduction of 30, 50, 70, 80 and 87.5 % in the [loo] direction, the rolled and annealed crystals develop “SC” texture only on the occasion of rolling with the reduction of 70 and 80 %. No “SC” texture develops in the crystal VO. Figure. 10 shows the relationship between the angle of rotation of [lOOI and the reduction in thickness. As the reduction is increased, the angle of rotation increases toward the (OOl)[llO] end orientation. Figure 11 gives the relationship between cold rolling reduction and the grain size of primary recrystallized matrix in the crystal OA and VO. When rolled 30 %, primary recrystallization completes at comparatively high temperature and grain size is large. As a reduction is increased, a finishing temperature of primary recrystallization becomes lower and grain size smaller. The texture of primary recrystallized matrix consists mainly of a quadruplet (113}(301) orientation regardless of rolling reduction in the crystal both OA
ACTA
410
METALLURGICA,
VOL.
14,
1966
c@ *
i
___’ .-._
FIU. 5(e). Transition bands and electron diffrwtion ptatterns in crystal OA rolled 70 %.
TAGUCHI
AND
SAKAKURA:
EFFECT
OF
AlN
ON
Si-Fe
FIQ. 5(b). Transition bands and electron diffraction patterns in crystal OA rolled 70 %.
and VO except ponent,
a doublet
additionally
of AlN
crystallography
precipitated wt.%), AlN:
(113)(110)
orientation,
is observed
as shown in Fig. 12.
4. Identi$cation The
that when rolled 87.5 ‘A a new com-
contained and
in the crystal
OA
in starting crystals
morphology (N as AIN:
of
AlN 0.0128
5A (N as AlN: 0.0050 wt.%) and VO (N as 0.0001 wt. %) have been investigated by
transmission
electron microscopy
and electron diffrac-
tion. Figure 13 shows AlN observed in the crystal OA by extraction carbon replica method. The structure of AlN was confirmed with
a = 3.104 A,
to be hexagonal
c = 4.965 A,
result of electron diffraction
close packed,
c/a = 1.6O,(s) as a
study of 39 precipitates
of AlN, except for a small number of AlN which were difficult to decide the structure as the thickness were
412
ACTA
METALLURGICA,
VOL.
14,
1966
FIG. 6. Primary recrystallized grains and transition bands on a rolling plane of crystal OA cold rolled 70 o/oand heated up to 600°C at the rate of lOOOC/hr. x 80
FIG. 9. (110) pole figure bf crystal OA rolled 70% and heated up to 900°C at the rata of lOO”C/hr. The marks crosses, black and white squares and triangles show major components.
too thick (> 0.2 p) f or electron diffraction crystal OA contains
study.
3 kinds of precipitates:
(1) the extremely large precipitates
which is plate-like
as shown in Fig. 13(A) are of small numbers, comparatively
large precipitates
The
namely (2) the
formed as needles of
about 0.5 p in width and about 5 ,u in length as shown in Figs. 13(B) and (C) are of small numbers, the fine precipitates
formed
or less in length and dispersed uniformly FIG. 7.
Effects of annealing temperature on grain size in the crystals OA, 28 and VO.
and (3)
as needles of about
1 ,u
as shown in
Figs. 13(D), (E), (F) and (G) are of great numbers. the other hand, in the crystal 5A, agglomerated
On AlN
are observed as shown in Figs. 14(A) and (B), and fine needle-like
constituents
such as found Furthermore, is observed
FIG. 8. Micro-etched surface of crystal OA rolled 70% and heated up to 900°C at the rate of lOO’C/hr. C-secondary appears in matrix. x 80
of about 1 ,u or less in length
in the crystal
OA are not observed.
in the crystal VO, no precipitate
of AlN
as shown in Fig. 15.
FIG. 10. The relationship between the angle of rotation
of [ 1001 and the reduction in thickness.
TAGUCHI
AND
SAKAKURA:
AlN
ON
413
EFFECT
OF
Si-Fe
as shown
in Fig. 18 with relationship
to the pseudo
habit plane of parent crystal and measuring the angles 8” and 8’ or 8. Table 4 summarizes
these measuring results for 36
needles and plates selected arbitrarily
in the crystal
OA and 5A, and for 1 needle after cold rolling and 5 needles after annealing in the crystal OA. Most of the needles are on the pseudo planes
and most
habit
(lOO},
of the longitudinal
and {120}, directions
of
needles are about O”, 14”, 27” and 37” from the (OOl), plane. and
The orientation
the parent
firstly,
relationships
crystal
the longitudinal
were
between needles
obtained
directions
as follows:
determined
from
the data 8” were plotted on a (001) standard projection of parent crystal. COLD .ROiLfNG REDUCTION
(%/.)
FIG. 11. The relationships between cold rolling reduction and primary grain size. 0 After completion of primary recrystallization. 0 During secondary recrystallization.
From
the
electron
microscopic
(001) plane, that is the specimen that in the crystal
AZN.
crosses. the on
and needle-like
orientation
relationship
between the plate-like AlN and the parent crystal OA may be obtained
directly
by comparing
from a diffraction in the circled
pattern with the [loo]
of plate-like
diffraction
micrographs.
study
AlN, the next
can be proposed
direction of
patterns were obtained
areas in electron
result of electron
orientation
studying planes
and {120},
relationships
the parallelism between
the needles appear to
planes stably. were
Secondly,
determined
by
of principal crystallographic
parent
crystal,
{loo),
{llO},
{ill},
{120}, {112}, (122) and (340}, and AlN, (10.8) to {lO.O}, Thus,
we
can
relationships
propose
the
which are common
following
orientation
to all of the needles,
the longitu-
dinal direction of plates (LD in Fig. 13(A)) determined the crystal OA. The diffraction
were made for 29
{21.2}to{21.0}and{11.8}to{11.0),from~’inTable4.
as shown below.
The
From the fact above,
form on {loo),,
surface, it appears
OA the plate-like
AlN grow with directionality 4.1 Plate-like
observation
These plottings
needles and the results are shown in Fig. 19(B) by
As a
of 7 precipitates
orientation
relationship
or From
these
longitudinal
{10.1}~1~
II{120},
(24
(12.2)AlN
11{122},
(2b)
results, directions
the theoretical
of needles using 2 conditions
that the needles grow on (lOO}, or {120}, have
the
orientation
equation (2a) or (2b).
:
we can decide
relationships
planes and
as described
in
In Fig. 19(A) dashed lines show
the trace of (lOO), and (120}, planes and full lines and (O@~)A~N [i2.0]AlN
11[ioo],
AZN.
4.2 Needle&e of the needle-like [OO.l]AlN, that assuming
that
being
(‘)
[il.o]AlN 11[ioo],
or
The
longitudinal
dotted lines show the series of poles of the longitudinal
direction
AlN was found to be parallel to the is c-axis,
analysis of the diffraction containing
II(0011,
the
as determined
crystallographic
the longitudinal
perpendicular
from
pattern in Fig. 13(B”). plane
direction
the Now,
(HKL),
of needles and
to the specimen
surface,
(001)
plane, is pseudo habit plane, it seems that the needles form on the pseudo
habit
{loo),,
{120},
and {340},
planes from the Fig. 16(A) showing the angle relationship between
rolling direction
[loo]
and longitudinal
directions of 122 needles. Figure 17 shows the crystallographic relation between a needle and the parent crystal.
These relations were determined by determin-
ing t‘le crystallographic planes {pq,r}AlN from the diffraction patterns, then plotting this poles on a standard
(0001)~~~
stereographic
projection
of AlN
FIG. 12. (110) pole figure of crystal OA rolled 87.5% heated up to 680°C at the rate of lOO”C/hr.
and
414
ACTA
FIG. 13. AIN precipitated
METALLURGICA,
in the crystal
(2a) or (2b), and dir Lection thtat satisfy the equation tht:n crosse( 3 points marked black and white circles she>w the p oles of theoretical longitudinal directions Among the 29 needles observed, the needles. mabjority of the poles are within 5” from the above Of
VOL.
14,
1966
OA and their electron
theoretical
diffraction
patterns.
poles except for the poles of AlN 15, 33, 34 and 37. The positions marked by tr iangle show the poles of the intersecting lines forme ‘d by 2 planes selected arbitrarily from all {lOO), and/or { 120}, planes. The poles which are near the PIositions marked
TAGUCHI
SAKAKURA:
AND
EFFECT
OF AlN
ON Si-Fe
FIG. 14. AlN precipitated in the crystal 5A and their electron diffraction patterns.
FIG. 15. Electron micrograph of the crystal VO.
by triangle, to
namely
be principal
in the dotted
longitudinal
Most of those observed
we use the directions principal longitudinal
area, are assumed
directions
of needles.
fall in these areas. Hereinafter, marked directions
by
triangle,
of needles.
as the
5. Behavior of needles contained in the cold rolled and annealed crystals Figure needle-like
20
shows
the
AlN precipitated
electron
micrographs
in the deformation
B, and B, of the crystal OA rolled 70%.
of band
From the
ACTA
416
IO I4
0
20
B Cao RUED
FEZ. 16.
METALLURGICA,
n&J WSTAL
3748 ti
$I53
(BZ-EVV4D.I
14,
6063
1966
70
76 w TOTAL
90 /55
Psuedo habit planes and number of needles formed OR these planes. (A) starting crystal, (B) crystal rolled 70%.
micrographs, it is found that the needles having about 1 p or less in length are not deformed during cold rolling, and d~tribu~ with the same size and shape as observed in the starting single crystal, and furthermore the needles are on the pseudo-habit {IOO}, or (120}, plane as shown by the relationship between lon~tud~al directions and etching pits in micrograph. Figure 16(B) shows the angle relationships between rolling direction and longitudinal directions of 155 needles. It may be seen here that 61% of these needles are on the planes within 4” of pseudo-habit
FIG. 17.
VOL.
Crystallographic relations between a needle and the parent crystal.
{loo}, and (lZO}, planes. Considering these results, we can confirm that ilne needles rotate during cold rolling with the rotation of parent crystal to form the deformation bands. Therefore, when rolled 70% to 80% the angle of rotation toward the formation of deformation bands is about 26”, and the poles of the principal longitudinal directions of needles shown by position of closed circles in Fig. 21(A) coincide with the principal longitudinal directions of needles in the
Fm. 18. (0001) standard projection of AlN.
TACUCHI
SAKARURA:
AND
EFFECT
OF
AlN
ON
Si-Fe
417
TABLE4. Precipitation d&a of needles (hk. 1) Plane Deviation (“)
H AlN No. ; 3 4 5
(HKL) Plane -
-
7
-
10 11 12 13 14
0 ::
0001
0
-
8 0
90
8
0 0
010 010 TOO 010
88 :
7210 ii00
8
::
90
ii00 otro
:: 0
Z 0
TOO TOO
0
TlOO
Configuration
90 90 90 90
1210 1210
Plate-like Plate-like Plate-like Plate-like Plate-like Plate-like
30 30
LD LD LD LD LD LD LD
c-Axis c-Axis c-Axis c-Axis c-Axis c-Axis / c-Axis
Needle-like Needle-like Needle-like Needle-like Needle-like Needle-like Needle-like
:: 0
2
Too
88
010
0
2201 2312
8
::
10 18
30 19
LD LD
/ c-Axis / c-Axis
Needle-libe Needle-like
17
010
0
oili
9
30
18
LD // c-Axis
Needle-like
18 19
010 ioo
0 90
1213 1324
f
38 40
0 13
LD LD
Needle-like Needle-like
20
Too
90
i2io
-
-
LD _I_c-Axis
;: 23
720 720 ZiO
-24 -23 67
-7270 1210
0
Z
0” 30
Needle-like Needle-like
210 210 r20 210
-59 -59 -:::
f232 23Tl 2201 2312
16 18
21 ::,
Needle-like Needle-like Needle-like Needle-like
26 30
2:
28 29 -31 -31 ---
0001 0001 0001 0001
Relationships betw~_~~i~ and
(“)
0 90
010
i
(“)
0’ ( = 3;:) - 0)
0”
32
TZO
28
iloo
/ c-Axis j c-Axis
8
32i2 %213
t
-1213 2112
2 5
i2is
2
LD IIc-Axis LD c-Axis
Needle-like Needle-like
LD LD
Ii c-Axis
c-Axis
Needle-like Needle-like
0
LD 11c-Axis
Needle-like
2: 66
Needle-like
33
740
-13
i2io
0
0
0
LD // c-Axis
Needle-like
34
a10
-76
3211
0
16
13
LD // c-Axis
Needle-like
Fig. No.
Fig. 13s Fig. 14b
Fig. 13b
Fig. %?a
Fin. 13n
Fig. 14a
Fig. 13f
35
340
34
-1210
0
0
0
LD 11c-Axis
Needle-like
36
3ZO
32
2027
2
60
30
LD [)c-Axis
Needle.like
37
ii0
-43
2113
2
39
0
LD jj c-Axis
Needle-like
38 39
-.
-
1210 1210
x
0 0
0 0
LD I/ c-Axis LD c-Axis
Needle-like Needle-like
Fig. 23d Fig. 230
40
-
-
0221
8
20
30
LD jl c-Axis
Needle-like
Fig. 23d
41
-
ii01
0
30
30
LD // e-Axis
Needle-like
Fig. 23f
42
-
2207
2
62
30
LD jj c-Axis
Needle-like
-
AlN No. 14 After cold rooling AlN No. 38-42 After annealing starting crystal shown by position of open circles. C-primary has the (~l)[lOO] orientation which is the same as the orientation of starting crystal. The agglomerated AlN in the starting crystal were observed as the destroyed fragments after cold rolling. Figure 22 shows the electron micrograph of needle-like AlN precipitated in the partially recrystallized matrix heated up to 620%. Primary appears in the matrix of deformation band on right side of Fig. 22. It must
be noticed that change of both size and ~stribution of needles does not occur during primary recrystsllizrttion in spite of the fact that needles are passed through the grain boundary, as proved by the existence of needles crossing over the boundary. Figure 23 gives the electron ~~rogr&p~ of needles precipit&~ in the crystal OA cold rolled and heated up to 850%. The change of configuration of needles is not recognized even after the secondary recrystallization occurs.
418
ACTA
METALLURGICA,
VOL.
14,
1966
FICA 19. (001) standard projection of crystal and poles of the longitudinal directions of needles plotted on the standard projection, (A) theoretical, (B) observed.
The data 8” and 8’ for needles shown in Figures 23(D), (E) and (F) are obtained from the diffraction patterns and summarized in Table 4, but the orientation relationships with the parent crystal is not decided because the orientation of primary recrystallized matrix is not clear. Figure 24 shows the amount of AlN in the crystal varied with the increase of annealing temperature. In the crystals OA, 1A and 3A, amount of AlN increases in the temperature range of 800” to lOOO”C,while in the crystals 2A and 4A, no change occurs in the same range. Though the correlation between the amount of additionally precipitated
AlN in the temperature range of 800”-1000°C and the grain size of the M-oriented primary recrystallized matrix in the same temperature range as shown in Fig. 7 is fairly reasonable to identify the additionally precipitated AlN as the effective inhibitor, the AlN described above does not appear to play an important and essential role in order to develop the “SC” texture. Because, when the crystal VO rolled is heated up to 85O”C, no secondary appears in spite of some increase in the amount of AlN as observed in Figs. 24 and 25. AlN effective for the secondary recrystallization texture exists up to 1lOO”C, but at higher temperature
FIG. 20. AlN precipitated in the crystal OA rolled 70 % and their electron diffraction patterns.
TAGUCHI
AND SAKAKURA:
EFFECT
OF
AlN
ON
Si-Fe
419
of either second phase impurities or a strong primary recrystallization texture. Many workers have reported successful attempts to obtain the strong (1 lO)[OOl] secondary recrystallization texture by the inhibition of impurity, such as N,c6) VN,(‘) S@j and SiO,.@) However nobody has reported successful study to obtain the strong (OOl)[lOO] secondary recrystallization texture by impurity inhibition. Recently, Detert’lO) reported the phenomena concerning the strong (OOl)[lOO] secondary recrystallization texture driven by gas metal interfacial surface energy. But the secondary recrystallization described in the present study has nothing to do with the surface energy because the C-secondary grows regardless of the purity and the thickness of crystal, the purity of annealing gas and the formation of surface scale during annealing. Though the texture inhibition may generally play a dominant role in the secondary recrystallization, a quadruplet (113)(301) M-oriented matrix observed in this study does not appear to show the strong texture inhibition. Because there is a large difference, namely 90”, in orientation between q-M, which have [113] zone axis and there is a fairly large difference, about 50”, in orientstion between M,-&, MS-M4 etc. which have [llO] zone axis. Therefore the impurity inhibition due to AlN, seems to play an important role for the development of (OOl)[lOO] oriented secondary recrystallization texture. The orientation of the primary recrystallized matrix is existence
FIG+. 21. (A). Stereographic projection showing the coincidence of poles of the longitudinal directions of AlN in deformation band B, and C-primary. (B) Stereographic projection showing the disagreement of poles of the longitudinal directions of AlN in deformation band B, and M, and M, primaries. (C) Stereographic projection showing the disagreement of poles of the longitudinal directions of AlN in C-primary and M-primary.
it begins to dissolve and is in solution completely at 1200°C. It seems that the majority of AlN at, 1200°C in Fig. 24 are the agglomerated AlN which vanish by long time annealing in hydrogen gas at 1200°C. Cracked ammonia gas is favorable to develop the “SC” texture, but nitrogen % of annealing atmosphere does not, give the essential influence to secondary recrystallization phenomena. DISCUSSION
OF
RESULTS
Secondary recrystallization of silicon iron crystals has been extensively studied in not only polycrystalline sheets but also single crystal sheets by many workers. In order for complete secondary recrystallization to occur the primary grains must, remain small relative to the larger grains that must consume them. Inhibition of normal grain growth may be achieved by the 12
FIG. 22. AlN precipitated in the crystal OA rolled 70% and heated up to 620°C at the rate of lOO’C/hr.
ACTA
420
METALLUROICA,
VOL.
14,
1966
Fro. 23. AlN precipitated in the crystal OA rolled 70 % and heated up t,o 850°C at the rate of lOO”C/hr and their electron diffraction patterns.
in the range
{120}, planes with the special orientation relationships
but there is a
with the parent crystal, and when rolled from 70 y. to
little difference in orientation in the reduction more than 87.5%. On the other hand, the grain size is
80 %, the angle of rotation toward the formation of deformation band is about 26” and the principal
almost the same in the reduction
longitudinal
approximately
a quadruplet
(113}(301)
of 30 %-87.5 ‘A cold rolling reduction,
more than 50% as
shown in Fig. 11. Nevertheless, C-secondary appears only in the range of 70 o/o-SOo/o cold rolling reduction. In order to explain these facts, we must introduce new conception As stated
above,
concerning AlN
the impurity
forms
on the
a
inhibition.
{lOO},
and/or
directions
of needle-like
AlN
coincide
with the principal longitudinal directions of needles in the starting crystal. There is no change of the size and
distribution
of
needle-like
primary recrystallization grain boundary
AlN,
even
if
the
and grain growth occurs and
passes through the needles.
Impurity
TAGUCHI
FIG. 24. Effect of
AND
SAKAKURA:
temperatureon the quantity of AlN.
inhibition effect of normal grain growth has been studied by many workers. However, the effect is discussed in the conception of “mechanical impurity inhibition” which is affected by the factors of shape, size and volume fraction as stated by Zener.02) We introduce a new conception of impurity inhibition effect caused by special orientation relationships between parent crystal and impurity. In the presence of impurity, elastic strains will be produced in parent crystal by the misfit of lattices. In this study, these strains will be in minimum state when the precipitation of AlN having the principal longitudinal directions
EFFECT
OF
AlN
ON
Si-Fe
421
as shown in Fig. 19(B) and having the special orient&tion relationships with the parent crystal as shown in equations (2e) and (2b) occurs. The migration of grain boundary passing through the AlN must be inhibited not to destroy the special orientation relationships by the grain growth. But, if these relationships are maintained, the migration of grain boundary will not be inhibited. The impurity inhibition just described is named “preferred orientation inhibition”. When rolled in the range from 70% to SO%, these relationships are maintained in B,-band as well as in (OOl)[lOO] orientation as a result of agreement of the principal longitudinal directions of AlN as shown in Fig. 21(A). Therefore, the “preferred orientation inhibition” must be ineffective for the growth of C-primary in B,-band. On the other hand, the “preferred orientation inhibition” will be effective for the grain growth of M-primary in band B, as shown in Fig. 21(B). The dependence of the primary grain growth on “preferred orientation inhibition” leads to a special growth selectivity. From the above consideration, C-primary is more favored to grow than M-primary, then the former obtains larger grain size during primary recrystallization and growth. When rolled in the range of less than 70 % or more than 80 %, these relationships are not maintained for the growth of C-primary. The “preferred orientation inhibition” in the presence of needle-like AlN is exhibited at the next 2 stages :
Fra. 25. AlN precipitated additionally in the crystal VO rolled to 70% and heated up to 850°C.
ACTA
422
METALLURGICA,
(1) Nucleation of secondary recrystallization. As the driving force in primary recrystallization is mainly debased by the strain energy which is estimated to be 10s ergs/em3, the preferred orientation inhibition is not so effective in the stage of primary recrystallization. But, the preferred orientation inhibition is effective for the grain gropith. Let on be the boundary energy of neighbouring M-primaries, (TQthe boundary energy between a growing primary and M-primaries, I)M, Do the average diameter of the M-primaries, growing. primary respectively. Equation (3), then gives the driving force or available energy per unit volume, E/V, for the growth of the primary which is incubating to secondary. (3)
I = IR + Ip
(4
Here I is the force due to impurities restraining boundary migration, In the mechanical ~ibition term and I, the preferred inhibition term. The needle-like AlN precipitated in the deformation band did not disappear nor change the size and distribution, then it seems that the impurity inhibition term f is equal to I, for the growth of C-primary while I is equal to In + Ip for the growth of Mprimary. As the driving force is estimated to be of the order of 105 ergs/ems, the driving force for normal grain growth or secondary recrystallization is greatly influenced by the value I. Therefore, C-primary increases in size than M-primary in the period of secondary nucleation. The critical size of C-primary for nucleation of secondary recrystallization is obtained from equation (3) by setting E/V > 0, I& = Do and I = 1~. The results are given by
it
1 on - - IRDX k
14,
1966
M-oriented primary recrystallized matrix is inhibited. Assuming a figure of 1000 ergs/cma (13) for the large angle grain boundary energy between C-primary and M-primary, C-M boundary is very movable. Therefore, C-primary above critical size will proceed to grow. In this study, AlN effective for the development of “SC” texture appears to be fine precipitates about 1 p or less in length. The orientation relationships between parent crystal and AlN shown in equations (2a) and (2b) were principally obtained by observation of AlN about 1 ,LLin length. However, these relationships may be reasonable in fine needles. CONCLUSIONS
When rolled from 70 % to 80 % and annealed, the (OOl)[lOO] oriented single crystals of 3% silicon iron containing needle-like AlN will thoroughly reproduce the initial (OOl)[lOO] orientation by secondary recrystallization, regardless of the purity and thiakness of crystals, and of the purity of annealing gas and the formation of surface scales. If AIN is absent, or ineffective due to wrong size and distribution even if the quantity of AlN is large, the normal grain growth of the quadruplet (113){301) oriented primary recrystallization texture occurs, but secondary recrys~llization does not occur. 2. The AIN which is effective to develop the (OOl)[lOO] oriented secondary recrystallization texture has the following characteristics : (1) The effective AlN is fairly fine needles, 1 ,U or less in length, and is readily dissolved into solution in a short time by heat treatment-say, five minutes at 1200°C, but reprecipitates while slow cooling. (2) These fine needles precipitate at 800”G1000°C. (3) The structure of these needles is hexagonal close packed, with a = 3.104 8, c = 4.965 A, c/a = 1.60, and the longitudinal direction of needles coincides with the c-axis of hexagonal lattice. (4) The relationship of orientations between needles and parent crystal was obtained by analysis of electron diffraction patterns as follows, 1.
E,v=n(g-$)-I
DC > DM . oc
VOL.
1
(5)
If the cold rolling reduction is out of the range from 70 % to 80 %, the value I, in equation (3) must be substituted by In + I,, then the critical size D, increases. (2) I~~~~itio~ of normal grain growth during The needle-like AlN secondary recrystalli.don. precipitated in the deformation band did not change the size and distribution up to the temperature of 1000°C. It is assumed that the inhibiting force due to these AlN is I, + Ip for the growth of M-oriented primary recrystallized matrix, but I, for C-secondary. Perhaps, AlN increased in the range of 800% to 1000°C as shown in Fig. 24 forms newly on the habit plane of M-primary, then the grain boundary migration of
or
P%1N
II(120$x
(4a)
{12.2)*,,
II (12%
(W
(5) Most of the needles appear to form on PO)cZ
or
{1201,
(5)
(6) The theoretical longitudinal directions of needles determined from the relationships (4a) or (4b) and (5) coincide with the observed directions approximately.
TAGUCHI
AND
SAKAKURA:
(7) The directions of the intersection lines formed by any two arbitrary planes selected out from all {lOO}, and/or (120}, planes are concentrated by the above mentioned theoretical directions and also by the observed directions. These directions are assumed to be principal directions of the needles. 3. When rolled from 70% to SO%, the (OOl)[lOO] oriented single crystals. of 3 y0 silicon iron reorient to form deformation bands which are 0.01-0.1 mm wide, related by 26” rotations clockwise and counter-clockwise about the normal of the (001) plane parallel to the rolling plane. The regions between the deformation bands, namely transition bands consist of a number of sub-bands as described by Walter and Koch. These transition bands have near {113)(301) orientation and near (OOl)[lOO] orientation which are assumed to be nuclei of primary recrystallization. 4. The (OOl)[lOO] oriented single crystal containing needle-like AlN cold rolled 70% and heated at the rate of lOO”C/hr begins to recrystallize at 550°C. Primary recrystallization grains having a quadruplet {113}(301) and (OOl)[lOO] orientations are observed to originate within the transition bands. Secondary recrystallization of (OOl)[lOO] oriented primary begins at 800°C and completes at 1000°C at the expense of the fine grained primary recrystallized matrix. 5. When cold rolled from 70 % to 80 % and annealed, the needle-like AlN in the (OOl)[lOO] oriented crystal is observed to change as follows:(1) The needles rotate during cold rolling along the reorientation of parent crystal to form the deformation bands, without slip deformation of needles and then the principal longitudinal directions of needles after rolling substantially coincide with the direction of (OOl)[lOO] orientation. (2) No change occurs in size and distribution of the needles during primary recrystallization, normal grain growth and secondary recrystallization. 6. The driving energy for secondary recrystallization is not surface energy. The mechanism for
EFFECT
OF
AlN
ON
Si-Fe
423
(001) [loo] oriented secondary recrystallization is proposed as follows :The principal longitudinal directions of needlelike AlN precipitated in the deformation bands produced by cold rolling with the reduction of 70 % to 80% coincide with the principal longitudinal directions of needles in (OOl)[lOO] orientation, namely C-primary, and do not coincide with the principal longitudinal directions in M-primary. C-primary may become relatively large in size than M-primary in the period of primary recrystallization and growth as a result of the difference of the coincidence of orientation relationships between AlN and parent crystal, and grow into secondary at the expense of the fine grained matrix. The inhibition caused by the special orientation relationships between precipitates and parent crystal is named “preferred orientation inhibition”. ACKNOWLEDGMENT
The authors are grateful to Dr. S. Nagashima for his having made several valuable suggestions regardThey offer ing preparation of the present study. sincere thanks also to Mr. K. Kuroki and Mr. M. Miyoshi for the kind help these gentlemen gave in transmission electron microscopy and X-ray pole figure work. REFERENCES 1. J. L. WALTER and W. R. HIBBARD, Trans. Met. Sot. AIME 212, 731 (1958). J. L. WALTER and E. F. KOCH, Acta Met. 11., 923 (1963). :: H. Hu, Actu Met. 10, 1112 (1962). 4. S. TAQUCHI, A. SAKAKURA,H. TAKECHI and H. T~gasmm CT&‘.Patent 5, 136, 666 (1964). 5. G. A. JEFFREY and G. S. PARRY, J. Chem. Phya. 25,406 (1955). 6. J. DIEDRICH, U.S. Patent 2, 802, 761 (1957). H. C. FIEDLER, Trans. Met. Sot. AIME 221, 1201 (1961). :: J. E. MAY and D. TURNBULL, Tram. Met. Sot. AIME 212, 769 (1958). 9. E. V. WALKER and Miss J. HOWARD, J. Iron Steel Inst.
194, 96 (1964).
10. K. DETERT. Acta Met. 7. 589 (19591. T&s. Met. SOL AIME 11. C. G. DUNN and J. L. WA&&, 218, 448 (1960). 12. C. ZENER. Trans. Met. Sot. AIME 175. 15 (1948). 13. C. G. D&N and K. T. AUST, Acta Met: 5, $68 (1957).
RECRYSTALLIZATION TEXTURES (OOl)[lOO] SINGLE CRYSTALS OF
SILICON
S. TAGUCHIt
IRON*
and A. SAKAKURAT
A study ~8s made of the effects of AlN on the recrystallization textures in cold rolled and annealed (OOl)[lOO] crystals of 3 % silicon iron and AlN w&s found to have 8 great effect on secondary recrystallizrttion textures. The influence of cold rolling reduction w8s investigated 8s well. The following 8re the results of these investigations. Cold rolled and annealed (OOl)[lOO] single crystals containing fine needle-like AlN about 1 p or under in length develop (OOl)[lOO] oriented secondary recrystallization textures at the expense of 8 quadruplet {113}(301) oriented primary recrystallized matrix, while those contrtining no AlN produce normal grain growth textures of primary recrystallized matrix. The crystal structure of AlN is hexagonal close packed, with a = 3.104 & c = 4.965 A, and the needle-like AIN forms on {IOO} x or {120}= planes of silicon iron with the orien’ation relationships of or
{lO.l)AlN
/I {120)1
{124AlN
11{]=}a
The mechanism of secondary recrystallization is expleined by the concept of “preferred orientation inhibition” which is derived from the above-mentioned relationships between AlN and silicon iron.
EFFETS
DE AIN SUR LES MONOCRISTAUX
TEXTURES DE RECRISTALLISATION (OOl)[lOO] DE Fe-3% Si LAMINES ET
SECONDAIRE RECUITS
DE
Les auteurs ont Btudii?les effets de AlN sur les textures de recristallisation des monocristaux (001) [loo] de Fe-3 ‘A Si lamin& et recuits. Le nitrure d’aluminium 8 un effet important sur les textures de recristallisation secondaire. L’influence du pourcentage de reduction lors du laminege 8 BtB aussi envisagke. Les monocristaux (001) [loo] lamin& et recuits qui contiennent des aiguilles de nitrures d’aluminium de l’ordre de 1 micron ou moins, presentent des textures de recristallisation secondaire orient&es influencees par l’orientation de recristallisation prim8ire de 18 metrice et qui est {I 13) (301). Les cristaux qui ne contiennent pas de nitrures d’aluminium prbsentent des textures de croissance normales de la matrice recristrtlli&e. La structure cristalline du nitrure d’aluminium est hexagonale avec a = 3,104 il, c = 4,965 A. Les aiguilles de nitrure se ferment sur les plans {lOO}a et {120}a du Fe-Si avec les relations d’orientations suivantes: {IO,IJA~N I/{120)~ {1%2}AlN
11{122}a
Le m&anisme de recristallisation secondaire est enfin interpret& sur 18base du concept de “l’inhibition des orientations pr6f&entielles” qui d&oule des reletions d’orientation mention&es et existant entre le nitrure et le fer-silicium.
DER EINFLUB VON AlN AUF DIE SEKUNDliREN REKRISTALLISATIONSTEXTUREN IN KALT GEWALZTEN UND ANGELASSENEN (001) [loo]-3% EISENEINKRISTALLEN
Si-
Es wurde der EinfluD van AIN auf die Rekristallisationstexturen in kalt gewalzten und angelassenen (001) [loo]-Kristallen 8us 3 % Si-Eisen untersucht. Diese Untersuchungen brachten die folgenden Ergebnisse. Kalt gewelzte und angelassene (001) [loo]-Einkristalle mit feinem nadeliihnlichem AIN van 1 p oder weniger L&nge entwickeln (001) [ lOO]-orientierte sekundare Rekristallisationstexturen euf Kosten einer Quadruplet-{1 13) (301)-orientierten prim&r rekristallisierten Matrix. Die Kristallstruktur von AIN ist hexagonal dichtest gepaokt, mit a = 3,104 A, c = 4,965 A. Das nadelfijrmige ALN bildet sich auf { 10O}r~-oder { 120}a-Ebenen van Siliziumeisen, mit den Orientierungsbeziehungen {lO,l)~i~
oder
jl (120)~
{12,2}AlN 1) {122)a. Der Mechanismus der sekundiiren Rekristallisation wird erkliirt mit der Vorstellung einer “bevorzugten Orientierungsbehinderung”, welche van den obigen Beziehungen zwischen AlN und Siliziumeisen hergeleitet wird.
* Received February 2, 1965; revised Mey 11, 1965. t Technical Research Institute, Y&w&t8 Iron 8nd Steel Co., Ltd, Kitakyushu-Shi, ACTA
METALLURGICA,
VOL.
14, MARCH
1966
405
Japan.
406
ACTA
METALLURGICA,
VOL.
14,
1966
INTRODUCTION
in diameter which were prepared by the authors’ method,c4) i.e. cross rolling and annealing of comHeretofore numerous studies have been made concerning cold rolled 3 y0 silicon iron crystals initially mercial grade hot rolled 3 ‘A silicon iron sheets near (OOl)[lOO] and its recrystallization textures. containing a small amount of Al. In the final annealWalter and Hibbardo) reported that after 66% ing of this preparing process, the sheets were held for reduction by rolling the texture was noticed to be 20 hr at 1200°C and cooled at the rate of lOO”C/hr in consisting of the two symmetrical bands having such N50 gas:. The crystals with (001) plane within 5’ of orientations as were brought about by rotating the the plane of the sheets were selected and cut from the (OOl)[lOO] oriented crystal about 30” clockwise and sheets. These crystals were then subjected to pre-heat counter-clockwise about the normal of the rolling treats in order to change content, size and distribution plane, aud the annealed texture was near (OOl)[lOO]. of AlN. Tables 1, 2 and 3 summarize the conditions Walter and Kocht2) observed by transmission electron of pre-heat treats and the chemical analysis after microscopy the cold rolled textures and recrystallizatreats. These starting crystals were cold rolled with the reduction in thickness of 30, 50, 70, 80 and 87.5 % tion behavior of (OOl)[lOO] oriented high purity 3% silicon iron crystals. According to these authors, the respectively in the [lOO] direction. These cold rolled two sets of symmetrical deformation bands and crystals were heated at the rate of lOO’C/hr, annealed transition bands were formed when crystals were at 1200°C for 20 hr and cooled at the rate of lOO”C/hr. rolled. Hut3) reported that some of the orientation The gas used was cracked ammonia in heating and of recrystallized grain formed within the transition hydrogen in holding and cooling. band was (113) with the direction of rolling inclined Fine grained specimens were thinned to 0.05 mm about 17” to the [liO] direction. in thickness and placed in an integrating specimen The present authors noticed the effect of AlN on holder and the texture was determined by transmission recrystallization textures, especially on secondary X-ray method using MO-K, radiation. Large seconrecrystallization textures of 3 y0 silicon iron single dary grains and growth grains were etched by a special crystals initially (OOl)[lOO] oriented. The aim of the chemical solution, i.e. the solution of ferrous sulphate, present study is (firstly) to determine the relation sulphuric acid and water, and the texture was debetween recrystallization textures and AlN contained termined by optical goniometer. The chemical analysis in crystals, and (secondary) to clarify the characof AlN was carried out by the bromine-methyl acetate teristics of AlN which are of effect to develop seconmethod. Observation of precipitated AlN was made dary recrystallization textures, and (lastly) to discuss by transmission electron microscopy using carbon the mechanism of secondary recrystallization. extraction replica, and suitable foils were cut for examination by transmission electron microscopy EXPERIMENTAL PROCEDURE and electron diffraction pattern The single crystals used in this study were commercial purity 3% silicon iron with the (OOl)[lOO] $ N50 and N75 gas means N,50 volume o/0 + H,50 volume orientation. The crystals were chosen from the sheets % and N,75 volume % + Hz25 volume % mixture gas reconsisting of grains 1 mm in thickness and 50-100 mm spectively. TABLE 1. The relation between recrystallization textures and the conditions of pre-heat treat I
Crystal
Temp. (“C)
Time (hr)
Gas
Cooling rate (“Wr)
None
OA
Recrystallization textures ( %)
Chemical analysis of crystals (wt. %)
Conditions of preheat treat C
Si
acid sol. Al
total N
N as AlN
0.007
2.95
0.019
0.0142
0.010
2.89 2.92
0.018
0.0086
0.0128 -~ 0.0072 63 54
SC
PC
SC
90
5
5
90 50 90 40 5
N50
100
::
za
100
7 6”
2.90 2.91
18 ::
1250
20
N;O
100
4
2.85
21
6”: 89 59
;:
1200
::
H H:
100
0.0061
0.0126
0.0012 10
0.0001 1
0 0
::
vo
1200
20
Vat. *
100
0.006
0.028
0.0004
0.0001
5
90
;::
1200
:;
1200
5A
* Vat. means vacuum.
2.81
z:
4: 5 :8
1: 2; 6
5
TAGUCHI
FIG.
AND
SAKAKURA:
EFFECT
OF AIN ON Si-Fe
407
SC and SG textures PC texture 1. Macrostructuresof the annealedcrystalsshowing3 typical textures.
EXPERIMENTAL RESULTS 1. The pre-heat treats of crystals and recryst&zation textures Starting single crystals subjected to the pre-heat treat which is shown in Table 1 were rolled 70 “/o in the direction of [loo], then annealed. The relation between recrystallization textures and the conditions of pre-heat treat is shown in the last column of this table. Here, “SC” means the (OOl)[lOO] oriented secondary recrystallization texture consisting of grains with diameter of 10-100 mm, “PC” the quadruplet {113)(301) oriented normal grain growth texture of primary recrystallized matrix which is related by approximately 25-30’ rotations about two (110) axes of the (OOl)[lOO] orientation, and “SG” the doublet {011}(100) oriented secondary recrystallization texture. The macrostructures and the (100) pole figure of these 3 textures are shown in Figs. 1 and 2. Table 1 shows that in specimens OA, 1A and 3A containing some amount of AlN, “SC” textures develop, on the other hand, in specimens 10, 20 and VO containing little or no AlN, “PC” textures are found. But we must notice that although specimens 2A and 4A, which were subjected to pre-heat treat for a long time, contain AlN, their ‘SC” textures are rather poor ; especially in specimen 5A held for 20 hr at 125O”C, almost no “SC” texture From these results, it appears that the develops.
development of the (OOl)[lOO] oriented secondary recrystallization texture is dependent not only upon the quantity of AlN but also upon the precipitation size and distribution of AlN. Now starting single crystals were subjected to the pre-heat treat shown in Table 2: held in N, gas at 12OO”C,quenched or slow cooled, then cold rolled 70 %
.)9
,’
/
3
:z
\.\
FIG.2. [loo] pole figureof annealedcrystals.
408
ACTA TABLE
METALLURGICA,
Recrystallization textures ( %)
acid sol. Al
total N
SC
PC
SG
quench quench quench quench quench
0.021 18 22 25 25
0.0131 136 149 130 127
0.0081 89 92 78 63
5 5 5 5 5
90 90 90 90 90
5 5 5 5 5
N* N*
water quench water quench
24 16
82 81
29 1
5 5
90 90
5 5
N, N* N, N, N, N, N,
100 100 100 100 100 100 100
0.021 19 22 17 17 17 11
0.0138 139 148 125 114 97 82
0.0114 118 115 102 89 56 60
90 90 90 90 70 40 50
5 5 5 5 25 55 45
5 5 5 5 5 5 5
Cooling rate (“C/hr)
Time (hr)
Gas
AS 32 33 34 35 36
1200 1200 1200 1200 1200
l/12 1 5 10 20
N* N, N, N* N*
water water water water water
37 38
1200 1200
40 60
AS 42 43 44 45 46 47 48
1200 1200 1200 1200 1200 1200 1200
l/12 1 5 10 20 40 60
Zl?
3. The relation between recrystallization textures and the conditions of pre-heat treat III Chemical analysis of crystals (wt. %)
Conditions of pre-heat treat Crystal
AS 101 102 103 104 105 106
1966
Chemical analysis of crystal (wt. %)
Temp. (“C)
TABLE
14,
2. The relation between recrystallization textures and the conditions of pm-heat treat II
Conditions of pre-heat treat Crystal
VOL.
Recrystallization textures ( “/,)
Temp. (“C)
Time (hr)
Temp. of quench (“C)
Holding time (hr)
Cooling rate
acid sol. Al
N as N
N as AlN
SC
PC
SG
1300 1300 1300 1300 1300 1300
l/6 l/6 l/6 l/6 l/6 l/6
0 400 600 800 1000 1200
l/2 l/2 l/2 l/2 l/2
water quench water quench water quench water quench water quench
0.022 23 22 30 24 24
0.0098 74 94 88 92 97
0.0020 30 48 68 81 62
0 0 5 40 40 0
100 100 90 40 40 100
0 0 5 20 20 0
and annealed. The recrystallization textures were shown in the last column of this table. From these results, it is clear that even if the quantity of AlN is large, “SC” texture does not develop in the crystals quenched from the pre-heat temperature, and AlN effective for the development of “SC” texture appears to be line precipitates that may precipitate during slow cooling and is estimated to be from 0.0033 (= 0.0114-0.0081) to 0.0023 (= 0.0115-0.0092) wt. % N as AlN in quantity. And it seems that the chemical analysis value of N as AlN is attributed largely to the agglomerated AlN that is not in solution during the pre-heat treat. Starting single crystals were finally subjected to the pre-heat treat shown in Table 3: held for 10 min in N75 gas at the temperature of 1300°C so high that AlN may be in solution, quenched to the temperatures of O”, 400”, 600°, 800”, 1000’ and 1200% respectively and held at these temperatures for 30 min and then water quenched. AlN is reprecipitated by holding at these temperatures. From the recrystallization textures of crystals pre-heat treated, cold rolled 70 %
and annealed, it is clear that AlN effective for the development of “SC” texture precipitates in the range 8oo”c-1OOo”c. 2. Cold rolled, primary and secondary recrystallization textures in cold rolled (OOl)[lOO] oriented single crystals When rolled 70x, (OOl)[lOO] oriented single crystals reorient to form deformation bands (band B, and B, hereinafter) that are 0.01-0.1 mm in width and related by 26” rotations clockwise and counterclockwise about the normal of the (001) plane, as shown in Fig. 3. Figure 4 gives a stereogram of (110) poles of the cold rolled crystal OA. As shown in Fig. 4, the cold rolled texture consists mainly of a doublet {001}(210) orientation marked by black and white circles. Figure 5 gives electron micrographs showing the transition band structure which is the region between band B, and B,. Figure 5(a) shows C-band characterized by approximately (OOl)[lOO] orientation or near and Fig. 5(b) shows M-band approximately (113}(301) orientation or near. They are found to be
TAGUCHI
AND
SAKAKURA:
EFFECT
OF AlN
ON Si-Fe
409
bold rolling direction Fra.
3. Macroetched surf&e of (OOl)[lOO] crystal OA rolled 70 %. x 240
minor components of the cold rolled texture, marked by cross, black and white squares and triangles in Fig. 4. Furthermore, the existence of primaries having (OOl)[lOO] orientation and a quadruplet {113}(301) orientation was recognized as shown in Fig. 9 described later. They are designated C- and M-primaries. Then it would appear that minor components of cold rolled textures act as nuclei of primary recrystallization. M-band with a quadruplet (113)(301) orientation is related by approximately 25-30” rotations about two (110) axes of the (OOl)[lOO] oriented crystal. Here, the rotations about [ilO], i.e. M, and Ms, and about [iiO], i.e. Ms and M4 are distinguished. When heated at the rate of lOO”C/hr, primary grains begin to originate within the transition bands, as shown in Fig. 6, at the temperature of 550°C and primary recrystallization completes at 670°C and 710°C in crystal OA and VO respectively. When the temperature is increased, C oriented secondaries begin to grow at 800°C and complete at 1100°C in crystal OA, while the normal grain growth of M oriented primaries occurs in crystal VO. Figure 7 shows the grain size as a function of annealing temperature in the crystals OA, 2A and VO. It must be noticed that the matrix grain size appears independent of annealing temperature from 800°C to 1000°C in the crystal OA. Figures 8 and 9 give the micro-structure and texture of primary recrystallized matrix obtained from the crystal OA rolled 70% and heated up to 900°C at the rate of lOO”C/hr. The texture consists mainly of a
FIG. 4. (110) pole figure of crystals OA cold rolled 70 %. IX: random intensity.
quadruplet { 113}(301) orientation. The same results are also obtained in the crystal VO . These orientations are in good agreement with the orientations of “PC” texture shown in Fig. 2. Thus it is proved that the “PC” texture is normal grain growth texture of M oriented primary recrystallized matrix, while “SC” texture is produced by the growth of C oriented secondaries. 3. The inJEuenceof cold rolling reduction on the development of “SC” texture When the crystal OA is rolled with the reduction of 30, 50, 70, 80 and 87.5 % in the [loo] direction, the rolled and annealed crystals develop “SC” texture only on the occasion of rolling with the reduction of 70 and 80 %. No “SC” texture develops in the crystal VO. Figure. 10 shows the relationship between the angle of rotation of [lOOI and the reduction in thickness. As the reduction is increased, the angle of rotation increases toward the (OOl)[llO] end orientation. Figure 11 gives the relationship between cold rolling reduction and the grain size of primary recrystallized matrix in the crystal OA and VO. When rolled 30 %, primary recrystallization completes at comparatively high temperature and grain size is large. As a reduction is increased, a finishing temperature of primary recrystallization becomes lower and grain size smaller. The texture of primary recrystallized matrix consists mainly of a quadruplet (113}(301) orientation regardless of rolling reduction in the crystal both OA
ACTA
410
METALLURGICA,
VOL.
14,
1966
c@ *
i
___’ .-._
FIU. 5(e). Transition bands and electron diffrwtion ptatterns in crystal OA rolled 70 %.
TAGUCHI
AND
SAKAKURA:
EFFECT
OF
AlN
ON
Si-Fe
FIQ. 5(b). Transition bands and electron diffraction patterns in crystal OA rolled 70 %.
and VO except ponent,
a doublet
additionally
of AlN
crystallography
precipitated wt.%), AlN:
(113)(110)
orientation,
is observed
as shown in Fig. 12.
4. Identi$cation The
that when rolled 87.5 ‘A a new com-
contained and
in the crystal
OA
in starting crystals
morphology (N as AIN:
of
AlN 0.0128
5A (N as AlN: 0.0050 wt.%) and VO (N as 0.0001 wt. %) have been investigated by
transmission
electron microscopy
and electron diffrac-
tion. Figure 13 shows AlN observed in the crystal OA by extraction carbon replica method. The structure of AlN was confirmed with
a = 3.104 A,
to be hexagonal
c = 4.965 A,
result of electron diffraction
close packed,
c/a = 1.6O,(s) as a
study of 39 precipitates
of AlN, except for a small number of AlN which were difficult to decide the structure as the thickness were
412
ACTA
METALLURGICA,
VOL.
14,
1966
FIG. 6. Primary recrystallized grains and transition bands on a rolling plane of crystal OA cold rolled 70 o/oand heated up to 600°C at the rate of lOOOC/hr. x 80
FIG. 9. (110) pole figure bf crystal OA rolled 70% and heated up to 900°C at the rata of lOO”C/hr. The marks crosses, black and white squares and triangles show major components.
too thick (> 0.2 p) f or electron diffraction crystal OA contains
study.
3 kinds of precipitates:
(1) the extremely large precipitates
which is plate-like
as shown in Fig. 13(A) are of small numbers, comparatively
large precipitates
The
namely (2) the
formed as needles of
about 0.5 p in width and about 5 ,u in length as shown in Figs. 13(B) and (C) are of small numbers, the fine precipitates
formed
or less in length and dispersed uniformly FIG. 7.
Effects of annealing temperature on grain size in the crystals OA, 28 and VO.
and (3)
as needles of about
1 ,u
as shown in
Figs. 13(D), (E), (F) and (G) are of great numbers. the other hand, in the crystal 5A, agglomerated
On AlN
are observed as shown in Figs. 14(A) and (B), and fine needle-like
constituents
such as found Furthermore, is observed
FIG. 8. Micro-etched surface of crystal OA rolled 70% and heated up to 900°C at the rate of lOO’C/hr. C-secondary appears in matrix. x 80
of about 1 ,u or less in length
in the crystal
OA are not observed.
in the crystal VO, no precipitate
of AlN
as shown in Fig. 15.
FIG. 10. The relationship between the angle of rotation
of [ 1001 and the reduction in thickness.
TAGUCHI
AND
SAKAKURA:
AlN
ON
413
EFFECT
OF
Si-Fe
as shown
in Fig. 18 with relationship
to the pseudo
habit plane of parent crystal and measuring the angles 8” and 8’ or 8. Table 4 summarizes
these measuring results for 36
needles and plates selected arbitrarily
in the crystal
OA and 5A, and for 1 needle after cold rolling and 5 needles after annealing in the crystal OA. Most of the needles are on the pseudo planes
and most
habit
(lOO},
of the longitudinal
and {120}, directions
of
needles are about O”, 14”, 27” and 37” from the (OOl), plane. and
The orientation
the parent
firstly,
relationships
crystal
the longitudinal
were
between needles
obtained
directions
as follows:
determined
from
the data 8” were plotted on a (001) standard projection of parent crystal. COLD .ROiLfNG REDUCTION
(%/.)
FIG. 11. The relationships between cold rolling reduction and primary grain size. 0 After completion of primary recrystallization. 0 During secondary recrystallization.
From
the
electron
microscopic
(001) plane, that is the specimen that in the crystal
AZN.
crosses. the on
and needle-like
orientation
relationship
between the plate-like AlN and the parent crystal OA may be obtained
directly
by comparing
from a diffraction in the circled
pattern with the [loo]
of plate-like
diffraction
micrographs.
study
AlN, the next
can be proposed
direction of
patterns were obtained
areas in electron
result of electron
orientation
studying planes
and {120},
relationships
the parallelism between
the needles appear to
planes stably. were
Secondly,
determined
by
of principal crystallographic
parent
crystal,
{loo),
{llO},
{ill},
{120}, {112}, (122) and (340}, and AlN, (10.8) to {lO.O}, Thus,
we
can
relationships
propose
the
which are common
following
orientation
to all of the needles,
the longitu-
dinal direction of plates (LD in Fig. 13(A)) determined the crystal OA. The diffraction
were made for 29
{21.2}to{21.0}and{11.8}to{11.0),from~’inTable4.
as shown below.
The
From the fact above,
form on {loo),,
surface, it appears
OA the plate-like
AlN grow with directionality 4.1 Plate-like
observation
These plottings
needles and the results are shown in Fig. 19(B) by
As a
of 7 precipitates
orientation
relationship
or From
these
longitudinal
{10.1}~1~
II{120},
(24
(12.2)AlN
11{122},
(2b)
results, directions
the theoretical
of needles using 2 conditions
that the needles grow on (lOO}, or {120}, have
the
orientation
equation (2a) or (2b).
:
we can decide
relationships
planes and
as described
in
In Fig. 19(A) dashed lines show
the trace of (lOO), and (120}, planes and full lines and (O@~)A~N [i2.0]AlN
11[ioo],
AZN.
4.2 Needle&e of the needle-like [OO.l]AlN, that assuming
that
being
(‘)
[il.o]AlN 11[ioo],
or
The
longitudinal
dotted lines show the series of poles of the longitudinal
direction
AlN was found to be parallel to the is c-axis,
analysis of the diffraction containing
II(0011,
the
as determined
crystallographic
the longitudinal
perpendicular
from
pattern in Fig. 13(B”). plane
direction
the Now,
(HKL),
of needles and
to the specimen
surface,
(001)
plane, is pseudo habit plane, it seems that the needles form on the pseudo
habit
{loo),,
{120},
and {340},
planes from the Fig. 16(A) showing the angle relationship between
rolling direction
[loo]
and longitudinal
directions of 122 needles. Figure 17 shows the crystallographic relation between a needle and the parent crystal.
These relations were determined by determin-
ing t‘le crystallographic planes {pq,r}AlN from the diffraction patterns, then plotting this poles on a standard
(0001)~~~
stereographic
projection
of AlN
FIG. 12. (110) pole figure of crystal OA rolled 87.5% heated up to 680°C at the rate of lOO”C/hr.
and
414
ACTA
FIG. 13. AIN precipitated
METALLURGICA,
in the crystal
(2a) or (2b), and dir Lection thtat satisfy the equation tht:n crosse( 3 points marked black and white circles she>w the p oles of theoretical longitudinal directions Among the 29 needles observed, the needles. mabjority of the poles are within 5” from the above Of
VOL.
14,
1966
OA and their electron
theoretical
diffraction
patterns.
poles except for the poles of AlN 15, 33, 34 and 37. The positions marked by tr iangle show the poles of the intersecting lines forme ‘d by 2 planes selected arbitrarily from all {lOO), and/or { 120}, planes. The poles which are near the PIositions marked
TAGUCHI
SAKAKURA:
AND
EFFECT
OF AlN
ON Si-Fe
FIG. 14. AlN precipitated in the crystal 5A and their electron diffraction patterns.
FIG. 15. Electron micrograph of the crystal VO.
by triangle, to
namely
be principal
in the dotted
longitudinal
Most of those observed
we use the directions principal longitudinal
area, are assumed
directions
of needles.
fall in these areas. Hereinafter, marked directions
by
triangle,
of needles.
as the
5. Behavior of needles contained in the cold rolled and annealed crystals Figure needle-like
20
shows
the
AlN precipitated
electron
micrographs
in the deformation
B, and B, of the crystal OA rolled 70%.
of band
From the
ACTA
416
IO I4
0
20
B Cao RUED
FEZ. 16.
METALLURGICA,
n&J WSTAL
3748 ti
$I53
(BZ-EVV4D.I
14,
6063
1966
70
76 w TOTAL
90 /55
Psuedo habit planes and number of needles formed OR these planes. (A) starting crystal, (B) crystal rolled 70%.
micrographs, it is found that the needles having about 1 p or less in length are not deformed during cold rolling, and d~tribu~ with the same size and shape as observed in the starting single crystal, and furthermore the needles are on the pseudo-habit {IOO}, or (120}, plane as shown by the relationship between lon~tud~al directions and etching pits in micrograph. Figure 16(B) shows the angle relationships between rolling direction and longitudinal directions of 155 needles. It may be seen here that 61% of these needles are on the planes within 4” of pseudo-habit
FIG. 17.
VOL.
Crystallographic relations between a needle and the parent crystal.
{loo}, and (lZO}, planes. Considering these results, we can confirm that ilne needles rotate during cold rolling with the rotation of parent crystal to form the deformation bands. Therefore, when rolled 70% to 80% the angle of rotation toward the formation of deformation bands is about 26”, and the poles of the principal longitudinal directions of needles shown by position of closed circles in Fig. 21(A) coincide with the principal longitudinal directions of needles in the
Fm. 18. (0001) standard projection of AlN.
TACUCHI
SAKARURA:
AND
EFFECT
OF
AlN
ON
Si-Fe
417
TABLE4. Precipitation d&a of needles (hk. 1) Plane Deviation (“)
H AlN No. ; 3 4 5
(HKL) Plane -
-
7
-
10 11 12 13 14
0 ::
0001
0
-
8 0
90
8
0 0
010 010 TOO 010
88 :
7210 ii00
8
::
90
ii00 otro
:: 0
Z 0
TOO TOO
0
TlOO
Configuration
90 90 90 90
1210 1210
Plate-like Plate-like Plate-like Plate-like Plate-like Plate-like
30 30
LD LD LD LD LD LD LD
c-Axis c-Axis c-Axis c-Axis c-Axis c-Axis / c-Axis
Needle-like Needle-like Needle-like Needle-like Needle-like Needle-like Needle-like
:: 0
2
Too
88
010
0
2201 2312
8
::
10 18
30 19
LD LD
/ c-Axis / c-Axis
Needle-libe Needle-like
17
010
0
oili
9
30
18
LD // c-Axis
Needle-like
18 19
010 ioo
0 90
1213 1324
f
38 40
0 13
LD LD
Needle-like Needle-like
20
Too
90
i2io
-
-
LD _I_c-Axis
;: 23
720 720 ZiO
-24 -23 67
-7270 1210
0
Z
0” 30
Needle-like Needle-like
210 210 r20 210
-59 -59 -:::
f232 23Tl 2201 2312
16 18
21 ::,
Needle-like Needle-like Needle-like Needle-like
26 30
2:
28 29 -31 -31 ---
0001 0001 0001 0001
Relationships betw~_~~i~ and
(“)
0 90
010
i
(“)
0’ ( = 3;:) - 0)
0”
32
TZO
28
iloo
/ c-Axis j c-Axis
8
32i2 %213
t
-1213 2112
2 5
i2is
2
LD IIc-Axis LD c-Axis
Needle-like Needle-like
LD LD
Ii c-Axis
c-Axis
Needle-like Needle-like
0
LD 11c-Axis
Needle-like
2: 66
Needle-like
33
740
-13
i2io
0
0
0
LD // c-Axis
Needle-like
34
a10
-76
3211
0
16
13
LD // c-Axis
Needle-like
Fig. No.
Fig. 13s Fig. 14b
Fig. 13b
Fig. %?a
Fin. 13n
Fig. 14a
Fig. 13f
35
340
34
-1210
0
0
0
LD 11c-Axis
Needle-like
36
3ZO
32
2027
2
60
30
LD [)c-Axis
Needle.like
37
ii0
-43
2113
2
39
0
LD jj c-Axis
Needle-like
38 39
-.
-
1210 1210
x
0 0
0 0
LD I/ c-Axis LD c-Axis
Needle-like Needle-like
Fig. 23d Fig. 230
40
-
-
0221
8
20
30
LD jl c-Axis
Needle-like
Fig. 23d
41
-
ii01
0
30
30
LD // e-Axis
Needle-like
Fig. 23f
42
-
2207
2
62
30
LD jj c-Axis
Needle-like
-
AlN No. 14 After cold rooling AlN No. 38-42 After annealing starting crystal shown by position of open circles. C-primary has the (~l)[lOO] orientation which is the same as the orientation of starting crystal. The agglomerated AlN in the starting crystal were observed as the destroyed fragments after cold rolling. Figure 22 shows the electron micrograph of needle-like AlN precipitated in the partially recrystallized matrix heated up to 620%. Primary appears in the matrix of deformation band on right side of Fig. 22. It must
be noticed that change of both size and ~stribution of needles does not occur during primary recrystsllizrttion in spite of the fact that needles are passed through the grain boundary, as proved by the existence of needles crossing over the boundary. Figure 23 gives the electron ~~rogr&p~ of needles precipit&~ in the crystal OA cold rolled and heated up to 850%. The change of configuration of needles is not recognized even after the secondary recrystallization occurs.
418
ACTA
METALLURGICA,
VOL.
14,
1966
FICA 19. (001) standard projection of crystal and poles of the longitudinal directions of needles plotted on the standard projection, (A) theoretical, (B) observed.
The data 8” and 8’ for needles shown in Figures 23(D), (E) and (F) are obtained from the diffraction patterns and summarized in Table 4, but the orientation relationships with the parent crystal is not decided because the orientation of primary recrystallized matrix is not clear. Figure 24 shows the amount of AlN in the crystal varied with the increase of annealing temperature. In the crystals OA, 1A and 3A, amount of AlN increases in the temperature range of 800” to lOOO”C,while in the crystals 2A and 4A, no change occurs in the same range. Though the correlation between the amount of additionally precipitated
AlN in the temperature range of 800”-1000°C and the grain size of the M-oriented primary recrystallized matrix in the same temperature range as shown in Fig. 7 is fairly reasonable to identify the additionally precipitated AlN as the effective inhibitor, the AlN described above does not appear to play an important and essential role in order to develop the “SC” texture. Because, when the crystal VO rolled is heated up to 85O”C, no secondary appears in spite of some increase in the amount of AlN as observed in Figs. 24 and 25. AlN effective for the secondary recrystallization texture exists up to 1lOO”C, but at higher temperature
FIG. 20. AlN precipitated in the crystal OA rolled 70 % and their electron diffraction patterns.
TAGUCHI
AND SAKAKURA:
EFFECT
OF
AlN
ON
Si-Fe
419
of either second phase impurities or a strong primary recrystallization texture. Many workers have reported successful attempts to obtain the strong (1 lO)[OOl] secondary recrystallization texture by the inhibition of impurity, such as N,c6) VN,(‘) S@j and SiO,.@) However nobody has reported successful study to obtain the strong (OOl)[lOO] secondary recrystallization texture by impurity inhibition. Recently, Detert’lO) reported the phenomena concerning the strong (OOl)[lOO] secondary recrystallization texture driven by gas metal interfacial surface energy. But the secondary recrystallization described in the present study has nothing to do with the surface energy because the C-secondary grows regardless of the purity and the thickness of crystal, the purity of annealing gas and the formation of surface scale during annealing. Though the texture inhibition may generally play a dominant role in the secondary recrystallization, a quadruplet (113)(301) M-oriented matrix observed in this study does not appear to show the strong texture inhibition. Because there is a large difference, namely 90”, in orientation between q-M, which have [113] zone axis and there is a fairly large difference, about 50”, in orientstion between M,-&, MS-M4 etc. which have [llO] zone axis. Therefore the impurity inhibition due to AlN, seems to play an important role for the development of (OOl)[lOO] oriented secondary recrystallization texture. The orientation of the primary recrystallized matrix is existence
FIG+. 21. (A). Stereographic projection showing the coincidence of poles of the longitudinal directions of AlN in deformation band B, and C-primary. (B) Stereographic projection showing the disagreement of poles of the longitudinal directions of AlN in deformation band B, and M, and M, primaries. (C) Stereographic projection showing the disagreement of poles of the longitudinal directions of AlN in C-primary and M-primary.
it begins to dissolve and is in solution completely at 1200°C. It seems that the majority of AlN at, 1200°C in Fig. 24 are the agglomerated AlN which vanish by long time annealing in hydrogen gas at 1200°C. Cracked ammonia gas is favorable to develop the “SC” texture, but nitrogen % of annealing atmosphere does not, give the essential influence to secondary recrystallization phenomena. DISCUSSION
OF
RESULTS
Secondary recrystallization of silicon iron crystals has been extensively studied in not only polycrystalline sheets but also single crystal sheets by many workers. In order for complete secondary recrystallization to occur the primary grains must, remain small relative to the larger grains that must consume them. Inhibition of normal grain growth may be achieved by the 12
FIG. 22. AlN precipitated in the crystal OA rolled 70% and heated up to 620°C at the rate of lOO’C/hr.
ACTA
420
METALLUROICA,
VOL.
14,
1966
Fro. 23. AlN precipitated in the crystal OA rolled 70 % and heated up t,o 850°C at the rate of lOO”C/hr and their electron diffraction patterns.
in the range
{120}, planes with the special orientation relationships
but there is a
with the parent crystal, and when rolled from 70 y. to
little difference in orientation in the reduction more than 87.5%. On the other hand, the grain size is
80 %, the angle of rotation toward the formation of deformation band is about 26” and the principal
almost the same in the reduction
longitudinal
approximately
a quadruplet
(113}(301)
of 30 %-87.5 ‘A cold rolling reduction,
more than 50% as
shown in Fig. 11. Nevertheless, C-secondary appears only in the range of 70 o/o-SOo/o cold rolling reduction. In order to explain these facts, we must introduce new conception As stated
above,
concerning AlN
the impurity
forms
on the
a
inhibition.
{lOO},
and/or
directions
of needle-like
AlN
coincide
with the principal longitudinal directions of needles in the starting crystal. There is no change of the size and
distribution
of
needle-like
primary recrystallization grain boundary
AlN,
even
if
the
and grain growth occurs and
passes through the needles.
Impurity
TAGUCHI
FIG. 24. Effect of
AND
SAKAKURA:
temperatureon the quantity of AlN.
inhibition effect of normal grain growth has been studied by many workers. However, the effect is discussed in the conception of “mechanical impurity inhibition” which is affected by the factors of shape, size and volume fraction as stated by Zener.02) We introduce a new conception of impurity inhibition effect caused by special orientation relationships between parent crystal and impurity. In the presence of impurity, elastic strains will be produced in parent crystal by the misfit of lattices. In this study, these strains will be in minimum state when the precipitation of AlN having the principal longitudinal directions
EFFECT
OF
AlN
ON
Si-Fe
421
as shown in Fig. 19(B) and having the special orient&tion relationships with the parent crystal as shown in equations (2e) and (2b) occurs. The migration of grain boundary passing through the AlN must be inhibited not to destroy the special orientation relationships by the grain growth. But, if these relationships are maintained, the migration of grain boundary will not be inhibited. The impurity inhibition just described is named “preferred orientation inhibition”. When rolled in the range from 70% to SO%, these relationships are maintained in B,-band as well as in (OOl)[lOO] orientation as a result of agreement of the principal longitudinal directions of AlN as shown in Fig. 21(A). Therefore, the “preferred orientation inhibition” must be ineffective for the growth of C-primary in B,-band. On the other hand, the “preferred orientation inhibition” will be effective for the grain growth of M-primary in band B, as shown in Fig. 21(B). The dependence of the primary grain growth on “preferred orientation inhibition” leads to a special growth selectivity. From the above consideration, C-primary is more favored to grow than M-primary, then the former obtains larger grain size during primary recrystallization and growth. When rolled in the range of less than 70 % or more than 80 %, these relationships are not maintained for the growth of C-primary. The “preferred orientation inhibition” in the presence of needle-like AlN is exhibited at the next 2 stages :
Fra. 25. AlN precipitated additionally in the crystal VO rolled to 70% and heated up to 850°C.
ACTA
422
METALLURGICA,
(1) Nucleation of secondary recrystallization. As the driving force in primary recrystallization is mainly debased by the strain energy which is estimated to be 10s ergs/em3, the preferred orientation inhibition is not so effective in the stage of primary recrystallization. But, the preferred orientation inhibition is effective for the grain gropith. Let on be the boundary energy of neighbouring M-primaries, (TQthe boundary energy between a growing primary and M-primaries, I)M, Do the average diameter of the M-primaries, growing. primary respectively. Equation (3), then gives the driving force or available energy per unit volume, E/V, for the growth of the primary which is incubating to secondary. (3)
I = IR + Ip
(4
Here I is the force due to impurities restraining boundary migration, In the mechanical ~ibition term and I, the preferred inhibition term. The needle-like AlN precipitated in the deformation band did not disappear nor change the size and distribution, then it seems that the impurity inhibition term f is equal to I, for the growth of C-primary while I is equal to In + Ip for the growth of Mprimary. As the driving force is estimated to be of the order of 105 ergs/ems, the driving force for normal grain growth or secondary recrystallization is greatly influenced by the value I. Therefore, C-primary increases in size than M-primary in the period of secondary nucleation. The critical size of C-primary for nucleation of secondary recrystallization is obtained from equation (3) by setting E/V > 0, I& = Do and I = 1~. The results are given by
it
1 on - - IRDX k
14,
1966
M-oriented primary recrystallized matrix is inhibited. Assuming a figure of 1000 ergs/cma (13) for the large angle grain boundary energy between C-primary and M-primary, C-M boundary is very movable. Therefore, C-primary above critical size will proceed to grow. In this study, AlN effective for the development of “SC” texture appears to be fine precipitates about 1 p or less in length. The orientation relationships between parent crystal and AlN shown in equations (2a) and (2b) were principally obtained by observation of AlN about 1 ,LLin length. However, these relationships may be reasonable in fine needles. CONCLUSIONS
When rolled from 70 % to 80 % and annealed, the (OOl)[lOO] oriented single crystals of 3% silicon iron containing needle-like AlN will thoroughly reproduce the initial (OOl)[lOO] orientation by secondary recrystallization, regardless of the purity and thiakness of crystals, and of the purity of annealing gas and the formation of surface scales. If AIN is absent, or ineffective due to wrong size and distribution even if the quantity of AlN is large, the normal grain growth of the quadruplet (113){301) oriented primary recrystallization texture occurs, but secondary recrys~llization does not occur. 2. The AIN which is effective to develop the (OOl)[lOO] oriented secondary recrystallization texture has the following characteristics : (1) The effective AlN is fairly fine needles, 1 ,U or less in length, and is readily dissolved into solution in a short time by heat treatment-say, five minutes at 1200°C, but reprecipitates while slow cooling. (2) These fine needles precipitate at 800”G1000°C. (3) The structure of these needles is hexagonal close packed, with a = 3.104 8, c = 4.965 A, c/a = 1.60, and the longitudinal direction of needles coincides with the c-axis of hexagonal lattice. (4) The relationship of orientations between needles and parent crystal was obtained by analysis of electron diffraction patterns as follows, 1.
E,v=n(g-$)-I
DC > DM . oc
VOL.
1
(5)
If the cold rolling reduction is out of the range from 70 % to 80 %, the value I, in equation (3) must be substituted by In + I,, then the critical size D, increases. (2) I~~~~itio~ of normal grain growth during The needle-like AlN secondary recrystalli.don. precipitated in the deformation band did not change the size and distribution up to the temperature of 1000°C. It is assumed that the inhibiting force due to these AlN is I, + Ip for the growth of M-oriented primary recrystallized matrix, but I, for C-secondary. Perhaps, AlN increased in the range of 800% to 1000°C as shown in Fig. 24 forms newly on the habit plane of M-primary, then the grain boundary migration of
or
P%1N
II(120$x
(4a)
{12.2)*,,
II (12%
(W
(5) Most of the needles appear to form on PO)cZ
or
{1201,
(5)
(6) The theoretical longitudinal directions of needles determined from the relationships (4a) or (4b) and (5) coincide with the observed directions approximately.
TAGUCHI
AND
SAKAKURA:
(7) The directions of the intersection lines formed by any two arbitrary planes selected out from all {lOO}, and/or (120}, planes are concentrated by the above mentioned theoretical directions and also by the observed directions. These directions are assumed to be principal directions of the needles. 3. When rolled from 70% to SO%, the (OOl)[lOO] oriented single crystals. of 3 y0 silicon iron reorient to form deformation bands which are 0.01-0.1 mm wide, related by 26” rotations clockwise and counter-clockwise about the normal of the (001) plane parallel to the rolling plane. The regions between the deformation bands, namely transition bands consist of a number of sub-bands as described by Walter and Koch. These transition bands have near {113)(301) orientation and near (OOl)[lOO] orientation which are assumed to be nuclei of primary recrystallization. 4. The (OOl)[lOO] oriented single crystal containing needle-like AlN cold rolled 70% and heated at the rate of lOO”C/hr begins to recrystallize at 550°C. Primary recrystallization grains having a quadruplet {113}(301) and (OOl)[lOO] orientations are observed to originate within the transition bands. Secondary recrystallization of (OOl)[lOO] oriented primary begins at 800°C and completes at 1000°C at the expense of the fine grained primary recrystallized matrix. 5. When cold rolled from 70 % to 80 % and annealed, the needle-like AlN in the (OOl)[lOO] oriented crystal is observed to change as follows:(1) The needles rotate during cold rolling along the reorientation of parent crystal to form the deformation bands, without slip deformation of needles and then the principal longitudinal directions of needles after rolling substantially coincide with the direction of (OOl)[lOO] orientation. (2) No change occurs in size and distribution of the needles during primary recrystallization, normal grain growth and secondary recrystallization. 6. The driving energy for secondary recrystallization is not surface energy. The mechanism for
EFFECT
OF
AlN
ON
Si-Fe
423
(001) [loo] oriented secondary recrystallization is proposed as follows :The principal longitudinal directions of needlelike AlN precipitated in the deformation bands produced by cold rolling with the reduction of 70 % to 80% coincide with the principal longitudinal directions of needles in (OOl)[lOO] orientation, namely C-primary, and do not coincide with the principal longitudinal directions in M-primary. C-primary may become relatively large in size than M-primary in the period of primary recrystallization and growth as a result of the difference of the coincidence of orientation relationships between AlN and parent crystal, and grow into secondary at the expense of the fine grained matrix. The inhibition caused by the special orientation relationships between precipitates and parent crystal is named “preferred orientation inhibition”. ACKNOWLEDGMENT
The authors are grateful to Dr. S. Nagashima for his having made several valuable suggestions regardThey offer ing preparation of the present study. sincere thanks also to Mr. K. Kuroki and Mr. M. Miyoshi for the kind help these gentlemen gave in transmission electron microscopy and X-ray pole figure work. REFERENCES 1. J. L. WALTER and W. R. HIBBARD, Trans. Met. Sot. AIME 212, 731 (1958). J. L. WALTER and E. F. KOCH, Acta Met. 11., 923 (1963). :: H. Hu, Actu Met. 10, 1112 (1962). 4. S. TAQUCHI, A. SAKAKURA,H. TAKECHI and H. T~gasmm CT&‘.Patent 5, 136, 666 (1964). 5. G. A. JEFFREY and G. S. PARRY, J. Chem. Phya. 25,406 (1955). 6. J. DIEDRICH, U.S. Patent 2, 802, 761 (1957). H. C. FIEDLER, Trans. Met. Sot. AIME 221, 1201 (1961). :: J. E. MAY and D. TURNBULL, Tram. Met. Sot. AIME 212, 769 (1958). 9. E. V. WALKER and Miss J. HOWARD, J. Iron Steel Inst.
194, 96 (1964).
10. K. DETERT. Acta Met. 7. 589 (19591. T&s. Met. SOL AIME 11. C. G. DUNN and J. L. WA&&, 218, 448 (1960). 12. C. ZENER. Trans. Met. Sot. AIME 175. 15 (1948). 13. C. G. D&N and K. T. AUST, Acta Met: 5, $68 (1957).