First-principles calculations of mechanical and thermodynamic properties of tungsten-based alloy

Abstract

The structural, mechanical and thermodynamic properties of tungsten-based alloys, including W0.5Ti0.5,W067Zr0.33,W0.666Ti0.1667Zr0.1667,W0.67Hf0.33 and W0.666Ti0.1667Hf0.1667, have been investigated in this paper by first-principles calculations based on density functional theory (DFT). The calculated elastic constants and mechanical stability criteria of cubic crystals indicated that all of these cubic alloys are mechanical stable. The mechanical properties, including bulk modulus (B), shear modulus (G), Young's modulus(E), ratio B/G, Poisson's ratio, Cauchy pressure and Vickers hardness are derived from the elastic constants Cij. According to calculated elastic modulus and Vickers hardness, the W0.666Ti0.1667Hf0.1667 alloy has the greatest mechanical strength. The Vickers hardness of these cubic alloys rank as follows: W0.666Ti0.1667Hf0.1667 > W0.67Zr0.33 > W0.666Ti0.1667Zr0.1667 > W0.5Ti0.5 > W0.67Hf0.33. Moreover, calculated ratio B/G, Poisson's ratio, Cauchy pressure indicated that the ductility of W0.666Ti0.1667Hf0.1667 alloy is the worst among these alloys. The ductility of these cubic alloys rank as follows: W0.67Hf0.33 > W05 Ti0.5 > W0.67Zr0.33 > W0.666Ti0.1667Zr0.1667 > W0.666Ti0.1667Hf0.1667. What is noteworthy is that both mechanical strength and ductility of W0.666Ti0.1667Hf0.1667 are greater than pure W. Finally, Debye temperature, melting point and thermal conductivity have been predicted through empirical formulas. All these results will provide scientific data for the study on new product development of electrode materials.