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Orientation relationship between the aluminium and silicon phases in an unmodified AlSi eutectic
Scripta M n ~ A ~ R u I ~ A et M_~TERIALIA
Vol
24 pp. 1975-!97S, 1990 Printed in the U.S.A.
Pergamon Press plc All rights r e s e r v e d
O R I E N T A T I O N R E L A T i O N S H i P BETWEEN THE ALUMiNIUM AND SILICON PHASES iN AN U N M O D I F I E D Ai-Si EUTECTiC
Liu Qing s Zhan~ Hu* Li Q i n g c h u n ~ SAnalysis and M _ a s u r e m e n t Cen~er, D e p a r t m e n t of Metals and Technology, Harbin Institute of TechnologF, Harbin 150006, P . R . C h i n a (Received March 23, 1990) (Revised August 6, 1990) introduction O r i e n t a t i o n r e l a t i o n s h i p s between the a l u m i n i u m and silicon phases in unmodified AI-Si euteotics were studied, and several reported. Shamsuzzoha et a.l [i] observed that the most frequent relationships between the a i u m i n i u m and silicon ph%ses in the bulk Ai-Si eutectic grown at the rate of the order lOOumS-I were: l! 1 i}]Si.,.","[2 I I]AI
Experimental An eutectic alloy of A l - 1 2 . 7 Z S i was p r e p a r e d from aluminium of 99.99~% p u r i t y and silicon of [email protected]% purity. Samples 10mm in d i a m e t e r and 4 0 0 a m in length w~re p r e p a r e d by d i r e c t i o n a l s o l i d i f i c a t i o n at the ~rowth rate of 100urnsand in the temperature g r a d i e n t of 12°C/am. For TEM examination, the 3 mm d i a m e t e r plates were cut by spark cutting and hand p o l i s h e d to about 0.1am. The specimens were then prepared by the ion milling method and examined in a Phiiips CMI2/STEM electron microscope. Since the width of the silicon flat platelets was small, the m i c r o d i f f r a e t i o n p a t t e r n s were obtained using a small size ochre:gent beam (200nm), making it easy to obtain high q u a l i t y Kikuchi patterns. Thus, the d i f f r a c t i o n patterns of exact zone axes can be obtained by a d j u s t m e n t of d o u b l e - t i l t holder with reference to Kikuchi
1975 0 0 3 6 - 9 7 4 8 / 9 0 $3.00 + .00 C o p y r i g h t (c) 1990 P e r g a m o n Press
plc
1976
U~%40DIFIED AI-Si
EUTECTIC
Vol.
24, No.
patterns, in this paper, after the exact zone axis was aligned to the beam d i r e c t i o n with reference to Kikuchi patterns, the microdiffraction patterns were taken with a small second condenser aperture size to show the d i f f r a c t i o n spots clearly. Results
and Discussion
Fig.l is a TEM image of a silicon phase in the specimen and the c o r r e s p o n d i n g diffraction. By assuming (I 1 1)Si as the twin plane, the d i f f r•a c t i o n pattern of the exact zone axis- [I T O] S 1 - (Fig ' Ib) was obtalned by careful adjustment of the d o u b l e % t i l t holder with reference to Kikuchi pattern; the tilt angles of two axes of the double-tilt holder (~_=ii.0 °, ~ : 2 . 2 °) were obtained from the meter reading of the holder• At the same tilt position of the double-tilt holder, the diffraction pattern of the adjacent aluminium phase was obtained with the beam on the aluminium phase by moving the specimen. It was found that the Kikuchi pole [I 1 2]AI was nearby• The d i f f r a c t i o n of the exact zone axis [i 1 2]AI was also obtained (Fig.lc) by an adjustment of the double-tilt holder; the tilt angles were ~ = 1 2 . 5 °, ~ = 1 6 . 1 °. Using the technique described by Liu [3], the angle between the d i r e c t i o n s [I I 0]Si and [I 1 2]AI was calculated being ~ = 1 3 . 8 9 °. The same method was used to obtain the m i c r o d i f f r a c t i o n patterns of the exact zone axis [i [ 0] of other silicon phases in the specimen, and it was found that the crystal d i r e c t i o n s [i 1 2~ of the adjacent aluminium phase were also near to the direction [i i 0]Si; the angles between [i I 0]Si and [I 1 2]AI changed within 4 ° to 14 ° Csee Fig.2,3,4, and 5). S h a m s u z z o h a et al. [i] found that the twin plane (i 1 l)si was parallel to {i 0 2}AI. However, from the results above the twin plane (I 1 I)8i was paralleI to (i i l)Ai (see Fig.l), (5 1 3)Al (see Fig.2), (I 3 2)AI (see Fig.4) and (4 1 2)AI (see Fig.5), although we also observed that (i 1 l)si//(2 0 I)AI (see Fig.3)• It can thus be concluded that no certain crystal plane of the aluminium phase was parallel to the internal twin plane (I I i) of the silicon phase. Conclusions In the bulk sample of an urlm~dified AI-Si eutectic grown at the growth rate of the order 100ums -* , there is no strict orientation relationship between the a l u m i n i u m and silicon phases, although the direction [I 1 2] of a l u m i n i u m phase is always near to the directions [1 [ 0] of the adjacent silicon phase. The angle between the d i r e c t i o n s [I [ O] S • and [i i 2]AI changes within 4 ° and 14 ° No certain . . crystal plane of a ~ u m l n l u m is parallel to the twin plane (i 1 i) of the silicon phase. References i. M. S h a m s u z z o h a and L. M. Hogan, J. Crystal Growth, 78, 429, (1986>. 2. M. S h a m s u z z o h a and L. M. Hogan, Metallography, 22, 37, (1989). 3. Liu Qing, Micron and M i c r o s c o p i c a Acta, 20, 3-4, 281, (1989).
I0
Vol.
2~,
No.
i0
UNMODIFIED
AI~Si
•
;
EUTECTIC
1977
t
el
FiG.I. (a)TEM image of a s i l i c o n phase. (b) t h e electron d}ffraction pattern of t h e z o n e a x i s [i T 0 ] $ i w h e r e cx=ll'0° and f~=2.2 ° , (c) the electron diffraction pattern of t h e z o n e a x i s [i 1 2 ] A I where c~=12.5 ° ~nd ~ = i 6 . f , and~=13.69"
8
t
t
•" e W
r
"
FIG.2. (a) T h e electron diffraction pattern of t h e z o n e a x i s where (x=12.0" a n d O = 1 . 5 ° , (b) the e l e c t r o n diffraction pattern z o n e a x i s [I 1 2] w h e r e c~=15.5" and ~=-i.~ ° , ~nd~,=4.62 ° .
m FIG.3, (a) T h e electron diffraction pattern of t h e z o n e a x i s where a = 4 . 0 ° a n d ~ = 2 0 . 3 ° , (b) t h e e l e c t r o n diffraction pattern z o n e a x i s [i 1 2 ] A I w h e r e ~ = 7 . 5 ° a n d ~ = I I . 4 ° , a n d s = 9 . 5 2 ° .
of
1978
U N M O D I F I E D AI-Si
EUTECTIC
Vol,
24, No.
w
e•
m FIG.4. (a) The electron d i f f r a c t i o n pattern of the zone axis [I ~ 0 ] ~ where ~ = - 5 . 0 ° and ~=1.3" , (b) the electron d i f f r a c t i o n pattern of zone axis [i 1 2]AI where ~ = - 1 5 . 0 ° and |3=-7.~ , ands=f3.18".
•
•
dP
•
@
6
m"
•
5o
0
@
•
$
e"
t
*
•
"
m
FIG.5. (a) The electron d i f f r a c t i o n pattern of the zone axis [i ~ 0 ~ where ~=24.0" and |~=-27.6", (b) the electron d i f f r a c t i o n pattern of zone axis [i 1 2]AI where ~=19.0" and ~ = - 2 2 . 1 ° , a n d s = 7 . 1 5 " .
i0
Vol
24 pp. 1975-!97S, 1990 Printed in the U.S.A.
Pergamon Press plc All rights r e s e r v e d
O R I E N T A T I O N R E L A T i O N S H i P BETWEEN THE ALUMiNIUM AND SILICON PHASES iN AN U N M O D I F I E D Ai-Si EUTECTiC
Liu Qing s Zhan~ Hu* Li Q i n g c h u n ~ SAnalysis and M _ a s u r e m e n t Cen~er, D e p a r t m e n t of Metals and Technology, Harbin Institute of TechnologF, Harbin 150006, P . R . C h i n a (Received March 23, 1990) (Revised August 6, 1990) introduction O r i e n t a t i o n r e l a t i o n s h i p s between the a l u m i n i u m and silicon phases in unmodified AI-Si euteotics were studied, and several reported. Shamsuzzoha et a.l [i] observed that the most frequent relationships between the a i u m i n i u m and silicon ph%ses in the bulk Ai-Si eutectic grown at the rate of the order lOOumS-I were: l! 1 i}]Si.,.","[2 I I]AI
Experimental An eutectic alloy of A l - 1 2 . 7 Z S i was p r e p a r e d from aluminium of 99.99~% p u r i t y and silicon of [email protected]% purity. Samples 10mm in d i a m e t e r and 4 0 0 a m in length w~re p r e p a r e d by d i r e c t i o n a l s o l i d i f i c a t i o n at the ~rowth rate of 100urnsand in the temperature g r a d i e n t of 12°C/am. For TEM examination, the 3 mm d i a m e t e r plates were cut by spark cutting and hand p o l i s h e d to about 0.1am. The specimens were then prepared by the ion milling method and examined in a Phiiips CMI2/STEM electron microscope. Since the width of the silicon flat platelets was small, the m i c r o d i f f r a e t i o n p a t t e r n s were obtained using a small size ochre:gent beam (200nm), making it easy to obtain high q u a l i t y Kikuchi patterns. Thus, the d i f f r a c t i o n patterns of exact zone axes can be obtained by a d j u s t m e n t of d o u b l e - t i l t holder with reference to Kikuchi
1975 0 0 3 6 - 9 7 4 8 / 9 0 $3.00 + .00 C o p y r i g h t (c) 1990 P e r g a m o n Press
plc
1976
U~%40DIFIED AI-Si
EUTECTIC
Vol.
24, No.
patterns, in this paper, after the exact zone axis was aligned to the beam d i r e c t i o n with reference to Kikuchi patterns, the microdiffraction patterns were taken with a small second condenser aperture size to show the d i f f r a c t i o n spots clearly. Results
and Discussion
Fig.l is a TEM image of a silicon phase in the specimen and the c o r r e s p o n d i n g diffraction. By assuming (I 1 1)Si as the twin plane, the d i f f r•a c t i o n pattern of the exact zone axis- [I T O] S 1 - (Fig ' Ib) was obtalned by careful adjustment of the d o u b l e % t i l t holder with reference to Kikuchi pattern; the tilt angles of two axes of the double-tilt holder (~_=ii.0 °, ~ : 2 . 2 °) were obtained from the meter reading of the holder• At the same tilt position of the double-tilt holder, the diffraction pattern of the adjacent aluminium phase was obtained with the beam on the aluminium phase by moving the specimen. It was found that the Kikuchi pole [I 1 2]AI was nearby• The d i f f r a c t i o n of the exact zone axis [i 1 2]AI was also obtained (Fig.lc) by an adjustment of the double-tilt holder; the tilt angles were ~ = 1 2 . 5 °, ~ = 1 6 . 1 °. Using the technique described by Liu [3], the angle between the d i r e c t i o n s [I I 0]Si and [I 1 2]AI was calculated being ~ = 1 3 . 8 9 °. The same method was used to obtain the m i c r o d i f f r a c t i o n patterns of the exact zone axis [i [ 0] of other silicon phases in the specimen, and it was found that the crystal d i r e c t i o n s [i 1 2~ of the adjacent aluminium phase were also near to the direction [i i 0]Si; the angles between [i I 0]Si and [I 1 2]AI changed within 4 ° to 14 ° Csee Fig.2,3,4, and 5). S h a m s u z z o h a et al. [i] found that the twin plane (i 1 l)si was parallel to {i 0 2}AI. However, from the results above the twin plane (I 1 I)8i was paralleI to (i i l)Ai (see Fig.l), (5 1 3)Al (see Fig.2), (I 3 2)AI (see Fig.4) and (4 1 2)AI (see Fig.5), although we also observed that (i 1 l)si//(2 0 I)AI (see Fig.3)• It can thus be concluded that no certain crystal plane of the aluminium phase was parallel to the internal twin plane (I I i) of the silicon phase. Conclusions In the bulk sample of an urlm~dified AI-Si eutectic grown at the growth rate of the order 100ums -* , there is no strict orientation relationship between the a l u m i n i u m and silicon phases, although the direction [I 1 2] of a l u m i n i u m phase is always near to the directions [1 [ 0] of the adjacent silicon phase. The angle between the d i r e c t i o n s [I [ O] S • and [i i 2]AI changes within 4 ° and 14 ° No certain . . crystal plane of a ~ u m l n l u m is parallel to the twin plane (i 1 i) of the silicon phase. References i. M. S h a m s u z z o h a and L. M. Hogan, J. Crystal Growth, 78, 429, (1986>. 2. M. S h a m s u z z o h a and L. M. Hogan, Metallography, 22, 37, (1989). 3. Liu Qing, Micron and M i c r o s c o p i c a Acta, 20, 3-4, 281, (1989).
I0
Vol.
2~,
No.
i0
UNMODIFIED
AI~Si
•
;
EUTECTIC
1977
t
el
FiG.I. (a)TEM image of a s i l i c o n phase. (b) t h e electron d}ffraction pattern of t h e z o n e a x i s [i T 0 ] $ i w h e r e cx=ll'0° and f~=2.2 ° , (c) the electron diffraction pattern of t h e z o n e a x i s [i 1 2 ] A I where c~=12.5 ° ~nd ~ = i 6 . f , and~=13.69"
8
t
t
•" e W
r
"
FIG.2. (a) T h e electron diffraction pattern of t h e z o n e a x i s where (x=12.0" a n d O = 1 . 5 ° , (b) the e l e c t r o n diffraction pattern z o n e a x i s [I 1 2] w h e r e c~=15.5" and ~=-i.~ ° , ~nd~,=4.62 ° .
m FIG.3, (a) T h e electron diffraction pattern of t h e z o n e a x i s where a = 4 . 0 ° a n d ~ = 2 0 . 3 ° , (b) t h e e l e c t r o n diffraction pattern z o n e a x i s [i 1 2 ] A I w h e r e ~ = 7 . 5 ° a n d ~ = I I . 4 ° , a n d s = 9 . 5 2 ° .
of
1978
U N M O D I F I E D AI-Si
EUTECTIC
Vol,
24, No.
w
e•
m FIG.4. (a) The electron d i f f r a c t i o n pattern of the zone axis [I ~ 0 ] ~ where ~ = - 5 . 0 ° and ~=1.3" , (b) the electron d i f f r a c t i o n pattern of zone axis [i 1 2]AI where ~ = - 1 5 . 0 ° and |3=-7.~ , ands=f3.18".
•
•
dP
•
@
6
m"
•
5o
0
@
•
$
e"
t
*
•
"
m
FIG.5. (a) The electron d i f f r a c t i o n pattern of the zone axis [i ~ 0 ~ where ~=24.0" and |~=-27.6", (b) the electron d i f f r a c t i o n pattern of zone axis [i 1 2]AI where ~=19.0" and ~ = - 2 2 . 1 ° , a n d s = 7 . 1 5 " .
i0