Theoretical prediction of high temperature mechanical, thermodynamic and surface O adsorption properties of W-Cu alloys: Advanced high temperature super strength alloy materials

Abstract

This paper constructs four alloy structural models of W₁₅Cu₁, W₁₄Cu₂, W₁₃Cu₃ and W₁₂Cu₄ as research objects. Based on phonon spectra analysis, the structure of W₁₂Cu₄ is unstable. Thus, the mechanical and thermodynamic properties for pure W, W₁₅Cu₁, W₁₄Cu₂ and W₁₃Cu₃ are studied using first-principles methods. The results show that the bulk modulus of W-Cu alloys exhibits the characteristics of high-temperature strength alloys. In particular, the bulk modulus of W₁₄Cu₂ and W₁₃Cu₃ increases rapidly with temperature increasing; Meanwhile, The W-Cu alloys at high temperatures exhibit low expansion behavior. The coefficient of thermal expansion of W₁₄Cu₂ at 1290 K starts to be lower than that of W, and decreases with temperature increasing. At 1370 K, the coefficient of thermal expansion of W₁₃Cu₃ begins to be lower than that of W₁₄Cu₂, which also decreases with temperature increasing. The W-Cu alloys at high temperatures exhibit excellent phonon thermal conductivity. The phonon thermal conductivity of W₁₄Cu₂ at 2230 K transcends pure W and then maintains a thermal conductivity of about 5.55Wm^-1K⁻¹. The phonon thermal conductivity of W₁₃Cu₃ at 2140 K begins to transcend W₁₄Cu₂, and also exceeds pure W at 2180 K, and increases rapidly with temperature increasing. At 0 K, the addition of Cu to W reduces the mechanical strength but increases the ductility.