In Part I of this paper, we have described a modification brought to the model of Lu (X.-G. Lu et al., Comput. Coupling Phase Diagr. Thermochem. 29 (2005) 49–55) in order to avoid extrapolation problems at high pressure and temperature. We now extend this approach to the study of a binary system: Os–Pt. For this, a complete description (equation of state) of Os at high pressure/high temperature is provided including the liquid phase. The thermodynamic assessment of the system Os–Pt has been carried out at ambient pressure by the Calphad method. All this study has been supported by first principles, special quasi-random structure (including under high pressure) and phonon calculations. Finally, using the high pressure description of metastable structures (hcp Pt and fcc Os), we have been able to obtain by extrapolation a complete description of Os–Pt system up to 500 GPa. Recent experimental data for Os–Pt system obtained up to 50 GPa at various temperatures up to 2300 °C may us allow to validate our modeling approach.

在本文的第一部分，我们描述了对 Lu 模型的修改（X.-G. Lu et al., Comput. Coupling Phase Diagr. Thermochem. 29 (2005) 49–55）以避免外推高温高压下的问题。我们现在将这种方法扩展到二元系统的研究：Os-Pt。为此，提供了在高压/高温下 Os 的完整描述（状态方程），包括液相。Os-Pt 系统的热力学评估是在环境压力下通过 Calphad 方法进行的。所有这些研究都得到了第一性原理、特殊的准随机结构（包括在高压下）和声子计算的支持。最后，使用亚稳态结构的高压描述（hcp Pt 和fccOs)，我们已经能够通过外推法获得高达 500 GPa 的 Os-Pt 系统的完整描述。在高达 2300 °C 的各种温度下获得高达 50 GPa 的 Os-Pt 系统的最新实验数据可以让我们验证我们的建模方法。