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Some observations on aluminum-thulium alloys
128
JOURNAL
OF
SOME OBSERVATIONS T. I. JONES*, Research Metallurgy
THE
LESS-COMMON
METALS
ON ALUMINUM-THULIUM
L. R. NORLOCK
Branch, Atomic Energy (Received
AND R. R. BOUCHER
of Canada,Ltd.,
September
ALLOYS
Chalk River, Ontario (Canada)
r8th, 1962)
SUMMARY Aluminum alloys containing 4-40 wt. y0 thulium have been prepared in sheet form down to 0.004 in. thick. The alloys were found to be two-phase: (~)aaluminum which contained less than 0.1 wt.% thulium in solution at 645°C and (2) an intermetallic compound, TmA13, possessing a simple cubic structure of the AuCus type with aa = 4.200 A. The two phases form a eutectic at IO & I wt.% thulium which melts at 645 f 3°C. A second intermetallic compound, with a face-centred cubic structure of the MgCuz type and ao = 7.770 A, was identified in an alloy containing originally 68 wt.% of thulium which was cooled relatively rapidly.
INTRODUCTION
Thulium is of interest to physicists since data on its neutron resonance scattering and transmission properties can provide further information on the structure of the nucleus. To measure these properties, thin sheets of the metal, 5 x 3 in., were required by the Reactor Physics Branch of A.E.C.L.1. A number of unsuccessful attempts were made to prepare the samples. The metal was found to be too brittle for cold rolling after annealing in argon and possessed too high an oxidation rate for hot rolling. Slightly better but still unsuccessful results were obtained when the metal was enveloped in copper before hot rolling. An alternative was to alloy the thulium with a second metal, whose resonance (s) did not interfere with those of thulium, to form an alloy with good rolling properties. The literature revealed that aluminum formed alloys with other rare earth metals, lanthanum, cerium and praseodymium2 and with yttriuma, group 3B. The aluminum rich alloys were composed of intermetallic compounds dispersed throughout dilute o(aluminum solid solutions. If thulium alloyed with aluminum in a similar manner, reasonably good rolling properties could be expected. PREPARATION
OF
ALUMINUM-THULIUM
SHEET
Alloys containing up to 20 wt.% of thulium were prepared by the direct dissolution of > 99 wt.% thulium in 99.99 wt.% aluminum at N IOOO~Cin vacua or under argon. Alloys of higher thulium contents were prepared under argon at temperatures up to 14oo’C. Relatively good agreement was obtained between the nominal compositions of the alloys, based on the initial weights of the components, and the final chemical analyses, as shown in Table I. * Present address:
Imperial
Aluminium
Co. Ltd., Swansea, United Kingdom. J. Less-Common
Metals, 5 (1963) 128--133
ALUMINUM-THULIUM TABLE ALLOY
Nominal wt. y0 thulium Wt. O/ thulium, by analysis
ALLOYS
129
I
COMPOSITIONS
IO 9.5 -
4 3.6 3.5 3.4
20 18.9 21.0 20.6
30 37.2 28.2 30.6
40 35.8 37.2 36.4
The alloys were cast into 318 x I x 5 in. graphite moulds heated to IOO’C. The 4 wt.“/b alloy was rolled without difficulty. The richer alloys were prone to edge cracking during rolling which could be reduced but not eliminated by first annealing overnight at 610°C. This treatment reduced the hardness of an as-cast 40 wt.% alloy from 58 to 4g VPN. Alloys containing 20 to 40 wt.% of thulium possessed hypereutectic structures which were partly spheroidised after heating at 610°C (Fig. I). The alloys were rolled to a range of thickness, 0.040 to 0.004 in., after a number of intermediate annealings. Radiographs showed that the rolled sheets were free from macrosegregation.
(4
(b)
Fig. I. Aluminum - 20 wt.% thulium alloy. Etching treatment: 2% NaOH solution. (a) As-cast structure, rapidly chilled by pouring into a IOO’C graphite mould. Primary TmAls crystals (see section on X-ray analyses) in a background of eutectic and oc-aluminum. (x 500). (b) As-rolled structure, annealed for 16 h at 61o’C followed by cold rolling. Primary TmAls crystals, partly spheroidised and partly ‘woken, in a background of n-aluminum and spheroidised eutectic-TmAls. (x 500)
THERMAL ANALYSES
Thermal analyses were carried out on alloys containing 0.1, 4, 8, IO, 12 and 15 wt.% of thulium, heated and cooled at 4 f z”C/min. These results and subsequent metallographic observations on the same specimens indicated a eutectic composition of IO & I wt.% of thulium (Fig. 2) with a eutectic temperature of 645 & 3°C. Since the J.
Less-Common
Metals,
5 (1963) 125-133
T. I. JONES, I,. R. NORLOCK, R. R. BOUCHER
130
0.x wt.% alloy contained a eutectic grain-boundary network the solubility of thulium in aluminum at 645°C was probably considerably less than 0.1 wt,“/b. Both the IZ and 15 wt.“/;, alloys showed pronounced gravitational segregation, which would be normal under conditions of slow cooling since the first phase to crystallize is considerably more dense than the remaining liquid alloy*.
(‘4 Slowly cooled structures
4’ Cjmin) of alu~~um-thulium alloys. Etching treatment: 2% NaOH solution. (a) 0.1 wt.% Tm, a-aluminum grains and a eutectic network. (X 400) (h) 8 wt.% Tm, primary a-aluminum dendrites in a background of eutectic. (X 40) (c) ~2 wt.:/, Tm, primary TmAls crystafs {grey) and eutectic. The primary crystals have segregated by gravitation. ( x 40)
Fig.
2.
I-
ALUMINUM-THULIUM ALLOYS
131
X-RAY ANALYSES X-ray diffraction powder patterns from alloys containing up to 40 wt.% of thulium (nominal) in the as-cast and spheroidised conditions all revealed two phases, aluminum and a simple cubic structure with a unit cell dimension of 4.200 & 0.005 A, using wavelengths of 1.5418 A for CuKa and 1.5405 A for CuKoll. As shown in Table II, the line densities were similar to those of UAls5 and NpAl$, both of which are isostructural with AuCua. Hence the composition of the phase was assumed to be TmA13 with a calculated density of 5.60 g/cma, based on one TmAL formula weight per unit cell. The stoichiometric composition of the phase would be 67.6 wt.% of thulium. TABLE II COMPARISON
TmA13 AND UA13 X-RAY
OFTHE
TmAla hkl
100
-
d spacings
Observed 4.121
III
2.931 2.399
200 210 211
2.082 I ,867 I.702
220 300, 310 311 222
I.478 I.395 I.323 1.261 1.208 1.161 I.118
110
221
320 321
400 410. 322 411,330 331 420 421 332
422 500, 430 5018 43’
I .o49 1.018 o.g886** o.g63o** o.g386** o.g157** 0.8952**
o.856g** o.8398**
5’12 333
0.8235** 0.8082**
520, 432
o.7799*’
(8)
-
Calculated 4.200 2.970 2.425 2.100
POWDER Observed TmA13
m s s
m-s
1.878 I.715
m-s
1.328 1.266 1.2I2 1.165 I.I22 1.050 I.019 0.9899 a.9635 a.9391 0.9165 o-8954 a.8573 0.8400 0.8237 0.8083 0.7799
m m-w s w-m w-m m W m m-w m m m-w w s w s s s
1.485 1.400
s s
DIFFRACTION
PATTERNS
intensities* UAl$ s s s s s s
m-s m-s m s w-m m m-s w m-s m m m m w-m m-s w-m m-s w-m not reported
* w, weak; m, medium; s, strong. ** Obtained with CuKal radiation
A further alloy containing initially 68 wt.% of thulium was prepared with the object of establishing whether the TmAla unit cell varied with composition. Thermal analysis results were not obtained with this alloy due to thermocouple failure on heating at 14ooOC. The alloy was allowed to.cool relatively rapidly. An X-ray diffraction powder of the alloy showed that it was composed mainly of a new phase possessing a face-centred cubic structure with a0 = 7.770 & 0.005 A. Since the line densities of the diffraction pattern were similar to those published for UAl$ and NpAl#, Table III, the compound was designated TmA12. The stoichiometric composition of this compound would be 75.8 wt.% of thulium with a calculated density of 6.31 g/cm3 J, Less-Common
Met&,
5 (1963) 128-133
T. I. JONES,
132
L. R. NORLOCK, TABLE
III
COMPARISONOF THE TmAln AND UAlz X-RAY TmAlg hkl
III 220
311 400 331 422 511, 333 440 53’ 620 533 622 444 7’1. 551 642 7312 553 800 733 822, 660 751, 555 840 9112 753 664 93’ 844 933
d spacings
Observed 4.489 2.746 2.346 I.945 1.784 I.587 I.497 I.375 1.3’5 1.230 1.186 not visible I.IZO I.089 1.03g*** 1.013*** o.g710*** o.g4g1*** o.g157*** o.Sg73*** 0.8684*** oJ352g*** 0.8282*** 0.8143*** 0.7929*** o.78og***
(A)
Calculated
44% 2.747 2.343 I.9425 I.783 1.586 I.495 I.374 I.314 I.229 1.185 I.171 I.I22 1.088 1.038 1.012 0.9713 0.9493 0.9157 0.8972 0.8687 0.8529 0.8283 0.8145 0.7930 0.7809
* VW, very weak; w, weak; m, medium; ** Observed for Np.418a. *** Obtained with CuKorl radiation.
Fig. 3. As-cast
R. R. BOUCHER
POWDER DIFFRACTIONPATTERNS Observed TmA12
intensities* UAL$
_
m-s S S w m S s m m m m not visible VW w s s w w s s w m m m-s m-s m
w-m s S w m S S m m m m-w not reported** w w-m S S VW VW m-s m-s m m m m not reported not reported
s, strong.
aluminum-68 wt.% thulium alloy. A background unidentified dispersed phases (as polished).
of TmAlz 200)
with at least
two
(x
J. Less-Common
Metals,
5 (1963)
128-133
ALUMIN-WM-T%ULIUM
I33
ALLOYS
based on 8 formula weights per unit cell. Faint, unidentified lines were present also on the X-ray film. Metallography showed that the alloy consisted of a continuous phase, presumably TmAla, and at least two dispersed phases (Fig. 3). The meta~o~aphic and X-ray ~f~action results are summarized in Fig. 4. The vertical lines representing TmAls and TmAls are broken since their compositional ranges were not established in the present work. The positions of the individual atoms in these types of phases have been shown schematically by RUNNALLS~.
1000
,’
LlPUlD
00
/ 800
-
/
ii f
;
/
/’
/ 645,3
1
i
I I
I
I I
I
i I
------_;
6oo~~:
400
t I.9
-
a-81
+
TmAl,
;i’
200 -
:; 1 ID
0
I 20
I 40
30
I 50
L 60
i
$ : j
: I III, 70
I I
60
WT. % THULIUM Fig. 4. Partial constitutions
diagram for aluminum-thulium.
REFERENCES P. P. SINGH, A .E.C.L.,
work to be published
The Properties of the Rare Earth Met& and Com#murzds, Bat&lie Memorial Institute, May 1959. C. E. LUNDIN AND D. T. KLODT, Trans. A%. Sot. Metals, 54 (1961) 168. B. C. ALLEN AND S. ISSEROW, Acta Met., 5 (1957) 465. R. E. RUNDLE AND A. S. WILSON, Acta Cry&, z (1949) 148. 0. J. C. RUNNALLS, J. Metals,
197 (1953)
1460.
J. Less-Common
Metals, 5 (1963) 128-133
JOURNAL
OF
SOME OBSERVATIONS T. I. JONES*, Research Metallurgy
THE
LESS-COMMON
METALS
ON ALUMINUM-THULIUM
L. R. NORLOCK
Branch, Atomic Energy (Received
AND R. R. BOUCHER
of Canada,Ltd.,
September
ALLOYS
Chalk River, Ontario (Canada)
r8th, 1962)
SUMMARY Aluminum alloys containing 4-40 wt. y0 thulium have been prepared in sheet form down to 0.004 in. thick. The alloys were found to be two-phase: (~)aaluminum which contained less than 0.1 wt.% thulium in solution at 645°C and (2) an intermetallic compound, TmA13, possessing a simple cubic structure of the AuCus type with aa = 4.200 A. The two phases form a eutectic at IO & I wt.% thulium which melts at 645 f 3°C. A second intermetallic compound, with a face-centred cubic structure of the MgCuz type and ao = 7.770 A, was identified in an alloy containing originally 68 wt.% of thulium which was cooled relatively rapidly.
INTRODUCTION
Thulium is of interest to physicists since data on its neutron resonance scattering and transmission properties can provide further information on the structure of the nucleus. To measure these properties, thin sheets of the metal, 5 x 3 in., were required by the Reactor Physics Branch of A.E.C.L.1. A number of unsuccessful attempts were made to prepare the samples. The metal was found to be too brittle for cold rolling after annealing in argon and possessed too high an oxidation rate for hot rolling. Slightly better but still unsuccessful results were obtained when the metal was enveloped in copper before hot rolling. An alternative was to alloy the thulium with a second metal, whose resonance (s) did not interfere with those of thulium, to form an alloy with good rolling properties. The literature revealed that aluminum formed alloys with other rare earth metals, lanthanum, cerium and praseodymium2 and with yttriuma, group 3B. The aluminum rich alloys were composed of intermetallic compounds dispersed throughout dilute o(aluminum solid solutions. If thulium alloyed with aluminum in a similar manner, reasonably good rolling properties could be expected. PREPARATION
OF
ALUMINUM-THULIUM
SHEET
Alloys containing up to 20 wt.% of thulium were prepared by the direct dissolution of > 99 wt.% thulium in 99.99 wt.% aluminum at N IOOO~Cin vacua or under argon. Alloys of higher thulium contents were prepared under argon at temperatures up to 14oo’C. Relatively good agreement was obtained between the nominal compositions of the alloys, based on the initial weights of the components, and the final chemical analyses, as shown in Table I. * Present address:
Imperial
Aluminium
Co. Ltd., Swansea, United Kingdom. J. Less-Common
Metals, 5 (1963) 128--133
ALUMINUM-THULIUM TABLE ALLOY
Nominal wt. y0 thulium Wt. O/ thulium, by analysis
ALLOYS
129
I
COMPOSITIONS
IO 9.5 -
4 3.6 3.5 3.4
20 18.9 21.0 20.6
30 37.2 28.2 30.6
40 35.8 37.2 36.4
The alloys were cast into 318 x I x 5 in. graphite moulds heated to IOO’C. The 4 wt.“/b alloy was rolled without difficulty. The richer alloys were prone to edge cracking during rolling which could be reduced but not eliminated by first annealing overnight at 610°C. This treatment reduced the hardness of an as-cast 40 wt.% alloy from 58 to 4g VPN. Alloys containing 20 to 40 wt.% of thulium possessed hypereutectic structures which were partly spheroidised after heating at 610°C (Fig. I). The alloys were rolled to a range of thickness, 0.040 to 0.004 in., after a number of intermediate annealings. Radiographs showed that the rolled sheets were free from macrosegregation.
(4
(b)
Fig. I. Aluminum - 20 wt.% thulium alloy. Etching treatment: 2% NaOH solution. (a) As-cast structure, rapidly chilled by pouring into a IOO’C graphite mould. Primary TmAls crystals (see section on X-ray analyses) in a background of eutectic and oc-aluminum. (x 500). (b) As-rolled structure, annealed for 16 h at 61o’C followed by cold rolling. Primary TmAls crystals, partly spheroidised and partly ‘woken, in a background of n-aluminum and spheroidised eutectic-TmAls. (x 500)
THERMAL ANALYSES
Thermal analyses were carried out on alloys containing 0.1, 4, 8, IO, 12 and 15 wt.% of thulium, heated and cooled at 4 f z”C/min. These results and subsequent metallographic observations on the same specimens indicated a eutectic composition of IO & I wt.% of thulium (Fig. 2) with a eutectic temperature of 645 & 3°C. Since the J.
Less-Common
Metals,
5 (1963) 125-133
T. I. JONES, I,. R. NORLOCK, R. R. BOUCHER
130
0.x wt.% alloy contained a eutectic grain-boundary network the solubility of thulium in aluminum at 645°C was probably considerably less than 0.1 wt,“/b. Both the IZ and 15 wt.“/;, alloys showed pronounced gravitational segregation, which would be normal under conditions of slow cooling since the first phase to crystallize is considerably more dense than the remaining liquid alloy*.
(‘4 Slowly cooled structures
4’ Cjmin) of alu~~um-thulium alloys. Etching treatment: 2% NaOH solution. (a) 0.1 wt.% Tm, a-aluminum grains and a eutectic network. (X 400) (h) 8 wt.% Tm, primary a-aluminum dendrites in a background of eutectic. (X 40) (c) ~2 wt.:/, Tm, primary TmAls crystafs {grey) and eutectic. The primary crystals have segregated by gravitation. ( x 40)
Fig.
2.
I-
ALUMINUM-THULIUM ALLOYS
131
X-RAY ANALYSES X-ray diffraction powder patterns from alloys containing up to 40 wt.% of thulium (nominal) in the as-cast and spheroidised conditions all revealed two phases, aluminum and a simple cubic structure with a unit cell dimension of 4.200 & 0.005 A, using wavelengths of 1.5418 A for CuKa and 1.5405 A for CuKoll. As shown in Table II, the line densities were similar to those of UAls5 and NpAl$, both of which are isostructural with AuCua. Hence the composition of the phase was assumed to be TmA13 with a calculated density of 5.60 g/cma, based on one TmAL formula weight per unit cell. The stoichiometric composition of the phase would be 67.6 wt.% of thulium. TABLE II COMPARISON
TmA13 AND UA13 X-RAY
OFTHE
TmAla hkl
100
-
d spacings
Observed 4.121
III
2.931 2.399
200 210 211
2.082 I ,867 I.702
220 300, 310 311 222
I.478 I.395 I.323 1.261 1.208 1.161 I.118
110
221
320 321
400 410. 322 411,330 331 420 421 332
422 500, 430 5018 43’
I .o49 1.018 o.g886** o.g63o** o.g386** o.g157** 0.8952**
o.856g** o.8398**
5’12 333
0.8235** 0.8082**
520, 432
o.7799*’
(8)
-
Calculated 4.200 2.970 2.425 2.100
POWDER Observed TmA13
m s s
m-s
1.878 I.715
m-s
1.328 1.266 1.2I2 1.165 I.I22 1.050 I.019 0.9899 a.9635 a.9391 0.9165 o-8954 a.8573 0.8400 0.8237 0.8083 0.7799
m m-w s w-m w-m m W m m-w m m m-w w s w s s s
1.485 1.400
s s
DIFFRACTION
PATTERNS
intensities* UAl$ s s s s s s
m-s m-s m s w-m m m-s w m-s m m m m w-m m-s w-m m-s w-m not reported
* w, weak; m, medium; s, strong. ** Obtained with CuKal radiation
A further alloy containing initially 68 wt.% of thulium was prepared with the object of establishing whether the TmAla unit cell varied with composition. Thermal analysis results were not obtained with this alloy due to thermocouple failure on heating at 14ooOC. The alloy was allowed to.cool relatively rapidly. An X-ray diffraction powder of the alloy showed that it was composed mainly of a new phase possessing a face-centred cubic structure with a0 = 7.770 & 0.005 A. Since the line densities of the diffraction pattern were similar to those published for UAl$ and NpAl#, Table III, the compound was designated TmA12. The stoichiometric composition of this compound would be 75.8 wt.% of thulium with a calculated density of 6.31 g/cm3 J, Less-Common
Met&,
5 (1963) 128-133
T. I. JONES,
132
L. R. NORLOCK, TABLE
III
COMPARISONOF THE TmAln AND UAlz X-RAY TmAlg hkl
III 220
311 400 331 422 511, 333 440 53’ 620 533 622 444 7’1. 551 642 7312 553 800 733 822, 660 751, 555 840 9112 753 664 93’ 844 933
d spacings
Observed 4.489 2.746 2.346 I.945 1.784 I.587 I.497 I.375 1.3’5 1.230 1.186 not visible I.IZO I.089 1.03g*** 1.013*** o.g710*** o.g4g1*** o.g157*** o.Sg73*** 0.8684*** oJ352g*** 0.8282*** 0.8143*** 0.7929*** o.78og***
(A)
Calculated
44% 2.747 2.343 I.9425 I.783 1.586 I.495 I.374 I.314 I.229 1.185 I.171 I.I22 1.088 1.038 1.012 0.9713 0.9493 0.9157 0.8972 0.8687 0.8529 0.8283 0.8145 0.7930 0.7809
* VW, very weak; w, weak; m, medium; ** Observed for Np.418a. *** Obtained with CuKorl radiation.
Fig. 3. As-cast
R. R. BOUCHER
POWDER DIFFRACTIONPATTERNS Observed TmA12
intensities* UAL$
_
m-s S S w m S s m m m m not visible VW w s s w w s s w m m m-s m-s m
w-m s S w m S S m m m m-w not reported** w w-m S S VW VW m-s m-s m m m m not reported not reported
s, strong.
aluminum-68 wt.% thulium alloy. A background unidentified dispersed phases (as polished).
of TmAlz 200)
with at least
two
(x
J. Less-Common
Metals,
5 (1963)
128-133
ALUMIN-WM-T%ULIUM
I33
ALLOYS
based on 8 formula weights per unit cell. Faint, unidentified lines were present also on the X-ray film. Metallography showed that the alloy consisted of a continuous phase, presumably TmAla, and at least two dispersed phases (Fig. 3). The meta~o~aphic and X-ray ~f~action results are summarized in Fig. 4. The vertical lines representing TmAls and TmAls are broken since their compositional ranges were not established in the present work. The positions of the individual atoms in these types of phases have been shown schematically by RUNNALLS~.
1000
,’
LlPUlD
00
/ 800
-
/
ii f
;
/
/’
/ 645,3
1
i
I I
I
I I
I
i I
------_;
6oo~~:
400
t I.9
-
a-81
+
TmAl,
;i’
200 -
:; 1 ID
0
I 20
I 40
30
I 50
L 60
i
$ : j
: I III, 70
I I
60
WT. % THULIUM Fig. 4. Partial constitutions
diagram for aluminum-thulium.
REFERENCES P. P. SINGH, A .E.C.L.,
work to be published
The Properties of the Rare Earth Met& and Com#murzds, Bat&lie Memorial Institute, May 1959. C. E. LUNDIN AND D. T. KLODT, Trans. A%. Sot. Metals, 54 (1961) 168. B. C. ALLEN AND S. ISSEROW, Acta Met., 5 (1957) 465. R. E. RUNDLE AND A. S. WILSON, Acta Cry&, z (1949) 148. 0. J. C. RUNNALLS, J. Metals,
197 (1953)
1460.
J. Less-Common
Metals, 5 (1963) 128-133