Y.J. Yang X.M. Tao W.J. Zhu Z.H. Long H.S. Liu Z.P. Jin
材料科学技术（英文）
Thermodynamic assessment of Ti-Co-Cu ternary system has been carried out by combining first-principle calculation and CALPHAD method. Firstly, formation enthalpies of stable and hypothesized compounds were calculated by first-principles method. Then, based on reported experimental information, a thermodynamic description of the Ti-Co-Cu ternary system was performed. Solution phases were treated as substitutional solutions of which excess Gibbs energies were formulated by Redlich-Kister polynomial, and the intermediate phases were described with sublattice models. All measured isothermal sections were reasonably reproduced. In addition, liquidus projection of this ternary system was further calculated, which may be useful for relevant materials processing.
关键词:
First-principle
,
assessment
,
phase diagram
,
First-principles
Benhai YU
金属学报(英文版)
The plane-wave pseudo-potential method within the framework of first-principles technique is used to investigate the fundamental structural properties of Si3N4. The calculated ground-state parameters agree quite well with the experimental data. Our calculation reveals that α-Si3N4 can retain its stability to at least 45 GPa when compressed below 300 K. No phase transition can be seen in the pressure range of 0--45 GPa and the temperature range of 0--300 K. Actually, the α→β transition occurs at 1600 K and 7.98 GPa. Many thermodynamic properties, such as bulk modulus, heat capacity, thermal expansion, Gruneisen parameter and Debye temperature of α-Si3N4 were determined at various temperatures and pressures. Significant differences in these properties were observed at high temperature and high pressure. The calculated results are in good agreement with the available experimental data and previous theoretical values. Therefore, our results may provide useful information for theoretical and experimental investigations of the N-based hard materials like α-Si3N4.
关键词:
First-principle
