Afew studies have been made of the Si-Ti-V phase diagram. [61Kom] determined the homogeneity range of the (V) solid solution at temperatures ranging from ...
P h a s e D i a g r a m E v a l u a t i o n s : S e c t i o n II
The Si-Ti-V System (S ili c o n- T i t a n i u m - V a n a d i u m ) By M. E n o m o t o National Research Institute for Metals surements. [77Fra] identified precipitates formed in the alloys having compositions near the Ti-V side.
Introduction Afew studies have been made of the Si-Ti-V phase diagram. [61Kom] determined the homogeneity range of the (V) solid solution at temperatures ranging from 1000 to 1500 *C in the composition range of Si < 6.8 at.% and Ti < 50 at.% using calcium-reduced vanadium (0.15 to 0.20 wt.% oxygen), iodide titanium, and silicon of 2 to 3 ppm impurities. Following these preliminary works, [65Gla] studied the constitution of an isothermal section at 800 *C in the range ofSi < 50 at.% using iodide titanium (99.9 wt.%), high purity S (99.8 wt.%), and carbon-reduced V (99.52 wt.%, containing 0.1 wt.% C and 0.2 wt.% O etc.). In the above studies, the alloy constitution and lattice parameter were determined by X-ray powder diffraction, metallography, and microhardness mea-
Table 1
Because of the keen interest in the development of superconducting materials, a number of authors studied the solubility of ternary alloying elements, e.g., Ti in V3Si, the influence thereof on the lattice parameter, mechanical, and electromagnetic properties of ternary compounds [65Say, 65Eli, 76Sha]. The solubility of Ti in the V6Si 5 compound was also studied by X-ray diffractometry [77Ste]. The existence of RMX2-type ternary compound, where R (Ti, Zr, Hf, Nb, and Ta) and M (V, Cr, Mn, Fe, Co, Ni, and Cu) are the transition elements of large and small atomic radii, respectively, and Xare AI, Ga, Si, and Ge, were first reported in this system by [65Gla]. [66Marl and [67Mar] determined the
Si-Ti-V Crystal S t r u c t u r e Data of Equilibrium Phases Composition
Phase
Terminal solid solution phases (aTi) .............................................
(~Ti).............................................. (V)(a)............................................ (Si) ................................................
r a n g e , at. %
0 to ~ 3V 0 to 0.5Si 0 to 100V 0 to 3.5Si 0 to 100Ti 0 to 7Si ~0Ti, ~ 0 V
Pearson symbol
Space group
Strukturbericht
hP2
P63/mmc
A3
Mg
c/2
Im3rn
A2
W
c12
lm3rn
A2
W
cF8
F d3m
A4
C(diamond)
tP32 hP16
P4z/n P63/mcm
... D88 type
Ti3P MnsSi3
tP36 tP36 oP8 oP8
P41212 P41212 Prom2
oF24
Pnma Fddd
... ... ... B27 C54
Si4Zrs ShZr5 TiSi BFe TiSi2
[87Muf2] [87Mur2] [65Gla]
cP8
Pm3n
A 15
Cr3Si
[65Say]
t132
I4/mcm
D8m
Si3W5
[65Gla] [65Gla]
o144
Immm
...
Nb6Sr~
[77Stel
hP9
P6222
C40
CrSi2
[65Gla]
...
P2t2t21
D23
...
[65Gla]
designation
Prototype
Reference
. . ~
Intermediate phases Ti3Si0a) ......................................... Ti5Si3 ............................................
25Si 35.5 to 39.5Si
Ti5Si4(b) ........................................ TisSi4(b) ........................................ TiSi(bXc) ......................................
44.4Si 44.24Si 50Si 50Si 66.7Si
- - ~
[65Gla]
0 to ~30V
TiSi 2 ..............................................
0to~5V V3Si.............................................. ~ 19 to 25.5Si 0 to ~ 15Ti 0 to ~ 20Ti VsSi3............................................ 37.5Si 0 to 12.5Ti V6Si 5 ............................................. VSi 2............................................................. TiVSi 2 ...........................................
45Si 0 to 36Ti 66.7Si 0 to 25Ti - 2 0 to 40V - 1 0 to 30Ti
...
(a) (V) forms a continuous bcc solid solution w i t h (13Ti). Co) No data on the solubility of V. (e) Two possibilities exist about the crystal structure of this compound.
Journal of Phase Equilibria Vol. 13 No. 2 1992
201
S e c t i o n II: P h a s e Diagram Evaluations
Weight 0
10
20
30
Percent
40 I i ........
Vanadium
50 t~T . . . . . . .
60 I'T . . . . . . . .
70 I i ........
80 Ii
90 .........
100
Ir .......
1910 C
L 1670~ .
.
.
.
.
- -
1605"C 1500
1000
(flTi,V)
882'C
850~
bOO .~j,~] ,~, (,__l aT)i 0
T
. . . . . . . . . . . . . . . . . .
10
. . . . . . . . .
. . . . . . . . .
20
30
Ti
40
Atomic
'. . . . . . . .
' . . . . . . .
60
50
PercenL
] . . . . . . . . .
70
~
r
~T$
90
80
. . . .
100
Vanadium
V
Fig. 1 Ti-Vbinary phase diagram. From [87Mur1].
Table 2
L a t t i c e P a r a m e t e r D a t a o f Si-Ti-V I n t e r m e d i a t e C o m p o u n d s
Phase
a
"l]3Si ......................................................................... (Til_xVx)sSi 3 ............................................................ "l]5Si 4 ....................................................................... "fiSi ..........................................................................
"liSi2......................................................................... (V 1_xTix.)3Si ..............................................................
(Vl_xTix.)sSi3 ............................................................ (Vl_xTix)sSiswithx = 0.33 ........................................ (Vl_xTi~6Si5withx = 0.67 ....................................... VSi2 ......................................................................... TiVSi2......................................................................
1.039 0.746 - 0.06Xv 0.7133 0.3618 0.6544 0.8253 0.4724+0.025XTi 0.4724+0.024XTi 0.4724+0.029XTI 0.9430+0.7XTi 1.610 1.635 0.4571 0.495
crystallographic structure and the lattice parameter o f this compound.
Binary Systems The binary Ti-V phase diagram (Fig. 1) is based on [87Murl]. A t high temperatures, the (13Ti) and (V) phases form a continuous series of bcc solid solution. B e l o w 850 ~ the m i s c i b i l i t y gap is present in the 13 phase giving rise to a monotectoid reaction, (13Ti) ",-" (aTi) + (V). In previ-
202
Lattice parameters, b
... ... ... 0.4973 0.3638 0.4783 . . . . . . . . . ... 0.758 0.769 ... 1.618
nm c
0.517 0.516 - 0.07Xv 1.2977 0.6492 0.4997 0.8540 . . .
. . .
. . . 0.4760+0.05X'n 0.489 0.500 0.6372 0.764
Reference
[87Mur2, 89Smi] [65Gla] [87Mur2, 89Smi] [87Mur2, 89Smi] [87Mur2, 89Smi] [65Sav] [65Gla, 65Eft] [76Sha, 77Ale] [65Gla] [77Ste] [77Ste] [87Mur2, 89Smi] [66Mar]
ous assessments [Hansen, Elliott, Shunk, 81Mur], both the ct/[13 + ( a T i ) ] and the 13/[[3 + (aTi)] boundaries were shown as a single curve. A recent study [89Wei] showed that the reported miscibility gap in the 13phase was p o s s i b l y due to the oxygen impurity and that neither a m i s c i b i l i t y gap nor a stable monotectoid was likely to occur in the binary Ti-V system, consistent with these assessments. The Si-Ti phase diagram (Fig. 2) is from [ 8 7 M u r l ] . Five intermediate compound phases and two terminal solid solutions exist. The liquidus is characterized by congruent melt-
Journal of Phase E q u i l i b r i a Vol. 13 No. 2 1992
P h a s e D i a g r a m E v a l u a t i o n s : S e c t i o n II
Weight 0 g~900
10
] .........
I'
~J-'
20 ~Z
Percent 40
30
.................
I' t . . . . . . .
I'
Silicon 50
I ......
i~ ~
.....
60
70
l "~ . . . . . . .
~. . . . . .
80 J~]"
90
100
~J'~''-"~
2000
L
1600 1670*C 1600 ]
o
1480~ 1414"C
1400
E~
1200
1000
(Si)~
800
--"'- (aTi) 6oo p. o ......... lb........
e'o
'~o ....
4'o
"
Atomic
Ti
00
.......
~'o
Percent
.....
Silicon
Si
Fig. 2 Ti-Si binary phase diagram. From [87Mur2].
Weight 1o
Percenl. Silicon :m 40 ,50
2o
0o
70
80
!to
~oo
2010~
2000 1870~
1925~
1910~ ~ ~ ; ~
g
~-~291a~6~c
,~oo (v) t
1600
7~
1
1640~
~,~
1~oo
%
i
e(i1 > 11605
i 1 i
1000
~.1
0
. . . . . . . . . . . . . . .
I0
i,,
. . . . .
gO
V
I .....
30
''''T
.
40
Atomic
.
.
.
.
.
.
.
.
T.
.
.
.
50
Percent
.
.
.
.
.
T ........
60
T .........
70
q .....
80
Silicon
,r,.[
.........
90
IO0
Si
Fig. 3 V-Si binary phase diagram. From [89Smi].
Journal of Phase Equilibria Vol. 13 No. 2 1992
203
Section
II' P h a s e D i a g r a m E v a l u a t i o n s
Si IO 90
,\
\,\
20
II
? .
50
