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Study of structural and thermodynamic properties of W and W₁₅Cr₁ at high temperatures and pressures by statistical moment method
Nguyen Quang Hoc, Hua Xuan Dat, Doan Quang Tuan, Quach Si Gia Khoa and Anh-Tuan Tran

The influence of high temperature and pressure on the structural and thermodynamic properties of W metal and W₁₅Cr₁ alloy is studied by the statistical moment method. In this paper, we build the theory of structural and thermodynamic properties for W₁₅Cr₁ alloy. We show the strong influence of anharmonic effects of the crystal lattice at high pressure on the lattice constant, thermal expansion coefficient and isochoric and isobaric heat capacities. The recalculated results for W metal and the new calculations for W₁₅Cr₁ alloy are compared with recent theoretical and experimental methods to verify the reliability in this paper. The results show that W₁₅Cr₁ alloy has the properties of today’s advanced materials. The expansion coefficient of W₁₅Cr₁ alloy is significantly lower than that of pure W, which shows that the addition of Cr can reduce the thermal expansion at high temperature. The heat release of pure W decreases with Cr doping at high temperature. The structural stability of W becomes more stable with Cr addition at high pressure.

Keywords: W and W₁₅Cr₁, structural and thermodynamic properties, high temperature and pressure, statistical moment method