TY - JOUR
T1 - Thermodynamic analysis of the Co-Al-C and Ni-Al-C systems by incorporating ab initio energetic calculations into the CALPHAD approach
AU - Ohtani, Hiroshi
AU - Yamano, Maki
AU - Hasebe, Mitsuhiro
N1 - Funding Information:
The authors gratefully acknowledge discussions with Dr. Y. Kimura and Prof. Y Mishima at Tokyo Institute of Technology. The authors are also grateful to Mr. H. Minooka for helpful work on the Al–C system. This work was partially supported by a Grant-in-Aid for Scientific Research (No. 14550720) from the Ministry of Education, Science, Sports and Culture of Japan.
PY - 2004/6
Y1 - 2004/6
N2 - The Co-Al-C ternary phase diagram has been constructed by combining ab initio energetic calculations with the CALPHAD approach, and the results have been compared with the Ni-Al-C ternary phase diagram obtained using the same procedure. In the thermodynamic analysis, special care was taken evaluating the expression of the free energy for the L12 and E21 structures. To treat these two structures as a continuous solution, the free energy was expressed using the (M, Al)3(Al, M)1(C, Va)1-type sublattice model. Because of the lack of experimental data, the thermodynamic properties of the E21 structure were evaluated using the Full Potential Linearized Augmented Plane Wave method. The calculated results show that the E21 phase in the Co-Al-C system is in equilibrium with fee Co, the B2-type intermetallic compound, and the graphite phase. This finding is in good agreement with previous experimental results. On the other hand, the E21 phase does not exist in the Ni-Al-C ternary system. The phase equilibrium of the Co-Ni-Al-C quaternary system is discussed, taking into account the two-phase separation between the E21 phase and the L12 phase.
AB - The Co-Al-C ternary phase diagram has been constructed by combining ab initio energetic calculations with the CALPHAD approach, and the results have been compared with the Ni-Al-C ternary phase diagram obtained using the same procedure. In the thermodynamic analysis, special care was taken evaluating the expression of the free energy for the L12 and E21 structures. To treat these two structures as a continuous solution, the free energy was expressed using the (M, Al)3(Al, M)1(C, Va)1-type sublattice model. Because of the lack of experimental data, the thermodynamic properties of the E21 structure were evaluated using the Full Potential Linearized Augmented Plane Wave method. The calculated results show that the E21 phase in the Co-Al-C system is in equilibrium with fee Co, the B2-type intermetallic compound, and the graphite phase. This finding is in good agreement with previous experimental results. On the other hand, the E21 phase does not exist in the Ni-Al-C ternary system. The phase equilibrium of the Co-Ni-Al-C quaternary system is discussed, taking into account the two-phase separation between the E21 phase and the L12 phase.
KW - Ab initio energetic calculations
KW - Phase diagram
KW - Phase separation
KW - Ternary carbide
KW - Thermodynamic analysis
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U2 - 10.1016/j.calphad.2004.08.003
DO - 10.1016/j.calphad.2004.08.003
M3 - Article
AN - SCOPUS:6344233516
VL - 28
SP - 177
EP - 190
JO - Calphad: Computer Coupling of Phase Diagrams and Thermochemistry
JF - Calphad: Computer Coupling of Phase Diagrams and Thermochemistry
SN - 0364-5916
IS - 2
ER -