thermodynamic re-assessment of the mn-c system · iac mse nürnberg, sep. 1-4, 2008 content 1. aim...
TRANSCRIPT
IAC
Thermodynamic Re-assessment of
the Mn-C System
D. Djurovic and B. Hallstedt,
Materials Chemistry, RWTH Aachen University, Kopernikusstrasse 16, 52074
Aachen, Germany
J. von Appen and R. Dronskowski
Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1,
52056 Aachen, Germany
1
MSE Nürnberg, Sep. 1-4, 2008IAC
Content
1. Aim of investigations
2. Previous assessment
3. Thermodynamic modeling
4. Results
5. Conclusion
2
MSE Nürnberg, Sep. 1-4, 2008IAC
To provide a thermodynamic description of the Fe-Mn-C system which is as accurate and reliable as possible, especially at low temperatures.
Fe-Mn-C
Fe-C Mn-C Fe-Mn[Gus1985] [Wit2004][Hua1990]
P. Gustafson, Scand. J. Metall., 14 (1985) 259V. T. Witusiewicz et al., J. Phase Equilib., 25 (2004) 346
W. Huang, Scand. J. Metall., 19 (1990) 26
1. Aim of investigations
3
MSE Nürnberg, Sep. 1-4, 2008IAC
Fig. 1. Calculated phase diagram of the Mn-C system
An inverse miscibility gap above 4800 K
2. Previous assessment
Incorrect appearance of the Mn2C (hcp) phase
at low temperature
4
MSE Nürnberg, Sep. 1-4, 2008IAC
3. Thermodynamic modeling
CBCC (Mn)1(C,Va)1CUB (Mn)1(C,Va)1
FCC (Mn)1(C,Va)1HCP (Mn)1(C,Va)0.5BCC (Mn)1(C,Va)3
a. Solid Solution Phases
The carbon solution in manganese is described by
interstitial solution models with one sublattice occupied by
manganese atoms and the other one occupied by the both
carbon and vacancies.
5
MSE Nürnberg, Sep. 1-4, 2008IAC
b. Stoichiometric Phases
Mn23C6, Mn3C, Mn5C2 and Mn7C3
∆°G(MnnCm,T)=a+bT+∆cp(MnnCm,T)
∆cp(MnnCm,T)=0 (The Neumann-Kopp rule)
6
MSE Nürnberg, Sep. 1-4, 2008IAC
800 900 1000 1100 1200 1300 1400
-16000
-14000
-12000
-10000
-8000
-6000
-4000
-2000
0 [Moa1971]
[Tan1971]
[Ben1974]
[Ere1974]
[Du1988]
[Zai2004]
µ(M
n),
Jm
ol-1
Temperature, K
800 900 1000 1100 1200 1300 1400
-16000
-14000
-12000
-10000
-8000
-6000
-4000
-2000
0 [Moa1971]
[Tan1971]
[Ben1974]
[Ere1974]
[Du1988]
[Zai2004]
µ(M
n),
Jm
ol-1
Temperature, K
800 900 1000 1100 1200 1300 1400
-16000
-14000
-12000
-10000
-8000
-6000
-4000
-2000
0
[Ere1974]
[Du1988]
[Zai2004]
µ(M
n),
Jm
ol-1
Temperature, K
800 900 1000 1100 1200 1300 1400
-16000
-14000
-12000
-10000
-8000
-6000
-4000
-2000
0 [Moa1971]
[Tan1971]
[Ben1974]
[Ere1974]
[Du1988]
[Zai2004]
µ(M
n),
Jm
ol-1
Temperature, K
Fig. 2. Experimental data on the chemical potential of Mn in various phase
equilibria
Mn23C6/Mn
Mn23C6/Mn3C
Mn5C2/Mn3C
Mn23C6/Mn5C2
Mn5C2/Mn7C3
Mn7C3/Graphite
E Moattar et al., Trans. Farad. Soc., 67 (1971) 2303
H. Tanaka et al., Trans.Japan Inst. Metals, 35 (1971) 997
R. Benz, Metall. Trans., 5 (1974) 2217
V.N. Eremenko et al., Tugo plavkie Karbidy (Russ.), G.V. Samsonov, ed., "Naukova Dumka", Kiev, Ukr. SSR, 1970, 204
Du Sichen et al., Metall.Trans. B, 19 (1988) 951
A. I. Zaitsev et al., Dokl. Akad. Nauk SSSR, 395 (2004) 632
7
MSE Nürnberg, Sep. 1-4, 2008IAC
b. Stoichiometric Phases
Metastable end-members Mn2C (hcp) and MnC (fcc)
∆°G(MnnCm,T)=a+bT+∆cp(MnnCm,T)
∆cp(MnnCm,T)=0 (The Neumann-Kopp rule)
8
MSE Nürnberg, Sep. 1-4, 2008IAC
Calculated phase diagram of the Mn-C system
Hua1990
this work
4. Results
9
MSE Nürnberg, Sep. 1-4, 2008IAC
Calculated phase diagram of the Mn-C system
Hua1990
this work
10
MSE Nürnberg, Sep. 1-4, 2008IAC
200 400 600 800 1000 1200 1400 1600 1800
-18000
-16000
-14000
-12000
-10000
-8000
-6000
-4000
-2000
0
Mn3C
Liqud
Graphite
FCC
HCP
Mn5C
2
Mn7C
3
Mn23
C6
CBCC
µ(M
n),
Jm
ol-1
Temperature, K
200 400 600 800 1000 1200 1400 1600 1800
-18000
-16000
-14000
-12000
-10000
-8000
-6000
-4000
-2000
0
µ(M
n),
Jm
ol-1
Temperature, K
200 400 600 800 1000 1200 1400 1600 1800
-18000
-16000
-14000
-12000
-10000
-8000
-6000
-4000
-2000
0
Mn3C
Graphite
CBCC
Liquid
Mn7C
3
Mn5C
2
HCP
FCC
Mn23
C6
µ(M
n),
Jm
ol-1
Temperature, K
β-Mn+ γ -Mn→α-Mn p 1130 K 1097 K
L→δ-Mn+ γ-Mn e 1506 K 1508 K
L→ε-Mn+ γ-Mn e 1502 K 1518 K
γ -Mn→a-Mn+ Mn23C6 e 1031 K 1036 K
ε -Mn→ γ -Mn+ Mn23C6 e 1260 K 1260 K
ε -Mn+ Mn3C→Mn23C6 p 1293 K 1305 K
ε -Mn + Mn5C2→Mn3C p 1323 K 1325 K
ε -Mn+ Mn7C3→Mn5C2 p 1363 K 1442 K
L + Mn7C3 → ε -Mn p 1573 K 1581 K
L+CGraphite→Mn7C3 p 1604 K 1600 K
Mn3C→ Mn5C2+ Mn23C6 e 1243 K 1240 K
Mn5C2→ Mn23C6+ Mn7C3 e
10
Calculated chemical potential of Mn in various phase equilibria
This
workLiterature
Hua1990
this work
11
MSE Nürnberg, Sep. 1-4, 2008IAC
∆fH°298 (J/mol of atoms)
Selected experiment
values Ab initio
(T=0K)
Previous
assessment Present work
MnC 27971 251 0
Mn2C -3858 -11128 -6000
-10677(1) Mn7C3
-9100(2) -6944 -11176 -10669
-10567(1) Mn5C2
-8900(2) -6476 -10978 -10565
Mn3C -9918(1) -6993 -10094 -9911
-10716(1) Mn23C6
-8465(3) -8381 -10622 -10706
Enthalpies of formation of binary manganese carbides
(1) The effusion method-A. I. Zaitsev et al., Dokl. Phys. Chem, 395 (2004) 94(2) High-temperature reaction calorimetry-S. V. Meschel et al., J. Alloys. Compd., 257 (1997) 227(3) Adiabatic oxygen combustion calorimetry-W. M. Dawson et al., Metall. Trans, 11 (1980) 1849
12
MSE Nürnberg, Sep. 1-4, 2008IAC
0.0 0.1 0.2 0.3 0.4
200
400
600
800
1000
1200
1400
1600
1800
2000
Tem
per
ature
(K
)
Mole fraction C
0.0 0.1 0.2 0.3 0.4
200
400
600
800
1000
1200
1400
1600
1800
2000
[Fen2007]
[Du1989]
[Das1995]
[Ma1991]
[Kat1993]
Tem
per
ature
(K
)
Mole fraction C
800 900 1000 1100 1200 1300 1400
-16000
-14000
-12000
-10000
-8000
-6000
-4000
-2000
0
µ(M
n),
Jm
ol-1
Temperature, K
800 900 1000 1100 1200 1300 1400
-16000
-14000
-12000
-10000
-8000
-6000
-4000
-2000
0
[Ere1974]
[Du1988]
[Zai2004]
µ(M
n),
Jm
ol-1
Temperature, K
V.N. Eremenko et al., Tugo plavkie Karbidy (Russ.), G.V.
Samsonov, ed., "Naukova Dumka", Kiev, Ukr. SSR, 1970,
204
Du Sichen et al., Metall.Trans. B, 19 (1988) 951
A. I. Zaitsev et al., Dokl. Akad. Nauk SSSR, 395 (2004) 632
J. Fenstad et al., Int. J. Mat. Res. 98 (2007) 10
V. Y. Dashevskii et al., Dokl. Chem. Tech. 343 (1995) 20
Z. Ma et al., Steel Res. 62 (1991) 481
Du Sichen et al., Metall.Trans. B, 20 (1989) 747
Katsnelson et al., ISIJ Int., 33 (1993), 1045.
Calculated chemical potential of Mn in various phase equilibria compared with
experimental data
Calculated phase diagram of the Mn-C system compared with experimental data
13
MSE Nürnberg, Sep. 1-4, 2008IAC
0.00 0.05 0.10 0.15 0.20 0.25 0.30
-0.8
-0.7
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0.0
0.1
0.2 [Kim2003]
[Tan1979]
[Kat1993]
Ln(γ
Mn)
Mole fraction C
0.00 0.05 0.10 0.15 0.20 0.25 0.30
-0.8
-0.7
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0.0
0.1
0.2
Ln(γ
Mn)
Mole fraction C
0.00 0.05 0.10 0.15 0.20 0.25 0.30
-0.8
-0.7
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0.0
0.1
0.2
Ln(γ
Mn)
Mole fraction C
Hua1990
this work
1628 K1673 K1723 K1773 K
Activity coefficients of manganese in Mn-C melts
E. –J. Kim. et al., Metall. Trans. B, 34 (2003) 51
Tanaka, Trans. Jpn. Inst. Met., 20 (1979), 516.
Katsnelson et al., ISIJ Int., 33 (1993), 1045.
14
MSE Nürnberg, Sep. 1-4, 2008IAC
Activity coefficients of carbon in Mn-C melts
0.00 0.05 0.10 0.15 0.20 0.25 0.30
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0 [Kim2003]
[Tan1979]
[Kat1993]
Ln(γ
C)
Mole fraction C
Hua1990
this work
1628 K1673 K1723 K1773 K
E. –J. Kim. et al., Metall. Trans. B, 34 (2003) 51
Tanaka, Trans. Jpn. Inst. Met., 20 (1979), 516.
Katsnelson et al., ISIJ Int., 33 (1993), 1045.
15
MSE Nürnberg, Sep. 1-4, 2008IAC
5. ConclusionThe thermodynamic description of Mn-C system has been updated in following ways:
• The Gibbs functions of the stable manganese carbides have been evaluated using recently published data of Zaitsev et al.
• The Gibbs function of the metastable Mn2C has been evaluated using enthalpy of formation obtained by ab initio calculation.
• New experimental data on the position of the liquidus line and theactivity of manganese and carbon in the Mn-C melts have been usedfor optimization of liquid phase.
The reevaluation of the phase equilibria and thermodynamic functions gives new thermodynamic description without the weaknesses of the previous one.
16
MSE Nürnberg, Sep. 1-4, 2008IAC
We want to thank DFG for financial support through the collaborative research centre SFB 761 “Steel - abinitio; quantum mechanics guided design of new Fe based materials"
Acknowledgement