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Further study on phase diagram of the iron-copper system
CALPWRI,
vo1.5,
~0.2,
pp.105-108,
o364-5916/81/020105-04$02.~/0 PergamonPress Ltd.
1981.
Printed in Great Britain.
FURTHERSTUDY ON PHASE DIAGRAM OF THE IRON-COPPER SYSTEM
Department
Mitsuhito Hasebe and Taiji Nishixawa of Materials Science, Faculty of Engineering, Tohoku University, Sendai, Japan
ABSTRACT. Partition of copper between austenite and ferrite system at 1000°C and 13OO’C was examined, and the parameter,
SieCu
i as a function
of
temperature
in Fe-Cu-Si interaction
and composition
was evaluated. Using a newly revised parameter, diagram of Fe-CU system has been re-calculated.
the
phase
In the previous paperlll, the authors reported on the calculation of phase diagrams of Fe-Cu and Co-Cu systems. After the publication, we found one flaw in the Fe-Cu system, which was that the A4 point is lowered by alloying of a minute amount of Cu, as shown in Fig.1, though Cu should not stabilize the 6 phase but the y phase. In order to revise the phase diagram on this point, the at&)/y equilibrium has been reexamined through experiments and calculations. The results obtained are reported below.
1850 ---
previous calculation present talc ulalion
r; 1800 al
5 5 1750 E E 1700
1650
Fe
2
4 FIG.~
6
8 at%Cu
Fe-Cu phase
_______________--L--Received 1 May 1981
105
10 diagram.
12
106
M. Hasebeand T. Nishizawa
2
Experimental
Equilibrium between u(6) and Y phases at 1000°C and 1300°C was Fe-6at%Cu alloy was cut into examined by diffusion couple experiments. crucible shape specimens with a hole of 3 mm diameter, in which a small piece The Ag-Si alloy was in liquid state at the of Ag-ZOat%Si alloy was inserted. equilibration temperatures, and steadily supplied the Fe-Cu alloy with Si, Fig.2 shows the which converted the yFe-Cu phase to the a(G)Fe-Cu phase. concentration profiles of Cu and Si in the vicinity of a(fi)/y phase boundary measured by electron-probe micro-analysis. The phase boundary compositions thus determined are listed in Table 1. TABLE 1
Experimental Results on a/y in Fe-Cu-Si System. a
Temperature 1273 K 1573 K
--
Equilibrium
Y
at%Cu
at%Si
at%Cu
at%Si
3.0
5.7
3.9
4.6
4.1
5.5 5.0 --__
4.2
8
6
-
-.
-.-c.u,. %.*a . I . lt 1++_c+-*_++Si -+-+I++*’
+*
cu l*<+i*z 1. l42, * . ;-‘-.-•-a-,, l++( Si,,+’ *A I*/ 2
I
0 ’ -100 FIG.2
-50
I
0 Distance
50
100
(pm 1
Concentration profile in Fe-6at%Cu/Ag-20%Si couple, heated at 13OO'C for 2 days.
3
Thermodvnamic
The free energy of y and a(6) phases was described in the same way as in the previous paper. It was decided by reexamining that two parameters should be altered as follows. [“G~;c]para- [OG~;c]para= 6280 - 3.347T instead of 3560 - 0.837T (J/mol) eq.(8.4) in the previous paper.
(J/m011
(1)
PHASE DIAGRAM
tR;eCulpara=12650 instead
of
+ 8.821T
OF IRON-COPPER SYSTEM
+ (-24050
107
+ 9.77Tf {xcu-
39720 - 4.2562 eq.(10.3] in the previous
se 1 fJ/mol)
(2)
paper.
regarding the free energy We had mistakenly used the parameter The new one was difference for Cu from the book by Kaufman and BernsteintZ]. taken from Table VII in the same book. The second parameter had been evaluated, assuming that it would be again on the This parameter was evaluated independent on composition. linearly on composition as expressed by the assumption that it depends following equation. (3) The value
for
experimental work
[Q~eCu]~ara in this
data
by Hellawell
by estimating
(aT,/ax,_)
8s
was
in eq.(2]
work
and
and Hume-Rothery
evaluated
above
given
those [3],
obtained
The phase diagram of mentioned parameters , and it
point
as shown in Fig.3.
the temperature gradient of K at A, and +1230 K at A4 polnt.
-2570
by arranging
on peritectic
in the phase
Tsl”e,lF
rGlk1P”‘” = 36700 - 0.949T
cr
A4
V
t z 5 z n
34
I
-
.
<
-6 Ok
E -6 ._ z a t g -10
[d&, I;“? -24050 +9.77 T
-12
-14
t Peritec
/
C
l
* Present work
I
1200 FIG.3
I
1
L
1400 Temperature EVslUatiOn
I
I
11 )O
1600 (K)
Of jQ&,,
fptra
was
boundary
Fe-Cu system was calculated again using was found that 6/y equilibrium near the
37
the
earlier
[Gzecu]zara
allotropic
The equilibria between should be corrected as shown in Fig.1. point or Cu phases at lower temperatures were not affected by the alternation parameters.
36
both
the A4
CT and y of the
108
M. Hasebe
4
and
T. Nishizawa
Conclush2n
The u(&)/Y equilibrium in Fe-Cu system was reexamined, and it was concluded that the parameters for the a(6) phase should be altered. The parameters for the y phase were not examined in this work, but it might be necessary to study them also, taking account of the recent results by Lindqvist and Uhrenius[41 on the y/liquid equilibrium. Beferences
1. M.Hasebe and T.Nishizawa, Calphad, 4, 83 (1980). 2. L.Kaufman and H.Bernstein, Computer Calculation of Phase Diagrams, p46 and plR5, Academic Press, New York, (1970). 3. A.Hellawell and W.Hume-Rothery, Phil. Trans. Roy. Sot. London, Ser.A, 249, 417 (1957). 4. P.-A.Lindqvistand B.Uhrenius, Calphad, 4, 193 (1980).
vo1.5,
~0.2,
pp.105-108,
o364-5916/81/020105-04$02.~/0 PergamonPress Ltd.
1981.
Printed in Great Britain.
FURTHERSTUDY ON PHASE DIAGRAM OF THE IRON-COPPER SYSTEM
Department
Mitsuhito Hasebe and Taiji Nishixawa of Materials Science, Faculty of Engineering, Tohoku University, Sendai, Japan
ABSTRACT. Partition of copper between austenite and ferrite system at 1000°C and 13OO’C was examined, and the parameter,
SieCu
i as a function
of
temperature
in Fe-Cu-Si interaction
and composition
was evaluated. Using a newly revised parameter, diagram of Fe-CU system has been re-calculated.
the
phase
In the previous paperlll, the authors reported on the calculation of phase diagrams of Fe-Cu and Co-Cu systems. After the publication, we found one flaw in the Fe-Cu system, which was that the A4 point is lowered by alloying of a minute amount of Cu, as shown in Fig.1, though Cu should not stabilize the 6 phase but the y phase. In order to revise the phase diagram on this point, the at&)/y equilibrium has been reexamined through experiments and calculations. The results obtained are reported below.
1850 ---
previous calculation present talc ulalion
r; 1800 al
5 5 1750 E E 1700
1650
Fe
2
4 FIG.~
6
8 at%Cu
Fe-Cu phase
_______________--L--Received 1 May 1981
105
10 diagram.
12
106
M. Hasebeand T. Nishizawa
2
Experimental
Equilibrium between u(6) and Y phases at 1000°C and 1300°C was Fe-6at%Cu alloy was cut into examined by diffusion couple experiments. crucible shape specimens with a hole of 3 mm diameter, in which a small piece The Ag-Si alloy was in liquid state at the of Ag-ZOat%Si alloy was inserted. equilibration temperatures, and steadily supplied the Fe-Cu alloy with Si, Fig.2 shows the which converted the yFe-Cu phase to the a(G)Fe-Cu phase. concentration profiles of Cu and Si in the vicinity of a(fi)/y phase boundary measured by electron-probe micro-analysis. The phase boundary compositions thus determined are listed in Table 1. TABLE 1
Experimental Results on a/y in Fe-Cu-Si System. a
Temperature 1273 K 1573 K
--
Equilibrium
Y
at%Cu
at%Si
at%Cu
at%Si
3.0
5.7
3.9
4.6
4.1
5.5 5.0 --__
4.2
8
6
-
-.
-.-c.u,. %.*a . I . lt 1++_c+-*_++Si -+-+I++*’
+*
cu l*<+i*z 1. l42, * . ;-‘-.-•-a-,, l++( Si,,+’ *A I*/ 2
I
0 ’ -100 FIG.2
-50
I
0 Distance
50
100
(pm 1
Concentration profile in Fe-6at%Cu/Ag-20%Si couple, heated at 13OO'C for 2 days.
3
Thermodvnamic
The free energy of y and a(6) phases was described in the same way as in the previous paper. It was decided by reexamining that two parameters should be altered as follows. [“G~;c]para- [OG~;c]para= 6280 - 3.347T instead of 3560 - 0.837T (J/mol) eq.(8.4) in the previous paper.
(J/m011
(1)
PHASE DIAGRAM
tR;eCulpara=12650 instead
of
+ 8.821T
OF IRON-COPPER SYSTEM
+ (-24050
107
+ 9.77Tf {xcu-
39720 - 4.2562 eq.(10.3] in the previous
se 1 fJ/mol)
(2)
paper.
regarding the free energy We had mistakenly used the parameter The new one was difference for Cu from the book by Kaufman and BernsteintZ]. taken from Table VII in the same book. The second parameter had been evaluated, assuming that it would be again on the This parameter was evaluated independent on composition. linearly on composition as expressed by the assumption that it depends following equation. (3) The value
for
experimental work
[Q~eCu]~ara in this
data
by Hellawell
by estimating
(aT,/ax,_)
8s
was
in eq.(2]
work
and
and Hume-Rothery
evaluated
above
given
those [3],
obtained
The phase diagram of mentioned parameters , and it
point
as shown in Fig.3.
the temperature gradient of K at A, and +1230 K at A4 polnt.
-2570
by arranging
on peritectic
in the phase
Tsl”e,lF
rGlk1P”‘” = 36700 - 0.949T
cr
A4
V
t z 5 z n
34
I
-
.
<
-6 Ok
E -6 ._ z a t g -10
[d&, I;“? -24050 +9.77 T
-12
-14
t Peritec
/
C
l
* Present work
I
1200 FIG.3
I
1
L
1400 Temperature EVslUatiOn
I
I
11 )O
1600 (K)
Of jQ&,,
fptra
was
boundary
Fe-Cu system was calculated again using was found that 6/y equilibrium near the
37
the
earlier
[Gzecu]zara
allotropic
The equilibria between should be corrected as shown in Fig.1. point or Cu phases at lower temperatures were not affected by the alternation parameters.
36
both
the A4
CT and y of the
108
M. Hasebe
4
and
T. Nishizawa
Conclush2n
The u(&)/Y equilibrium in Fe-Cu system was reexamined, and it was concluded that the parameters for the a(6) phase should be altered. The parameters for the y phase were not examined in this work, but it might be necessary to study them also, taking account of the recent results by Lindqvist and Uhrenius[41 on the y/liquid equilibrium. Beferences
1. M.Hasebe and T.Nishizawa, Calphad, 4, 83 (1980). 2. L.Kaufman and H.Bernstein, Computer Calculation of Phase Diagrams, p46 and plR5, Academic Press, New York, (1970). 3. A.Hellawell and W.Hume-Rothery, Phil. Trans. Roy. Sot. London, Ser.A, 249, 417 (1957). 4. P.-A.Lindqvistand B.Uhrenius, Calphad, 4, 193 (1980).