第一性原理计算Mo含量及压力对CrZrNbTiMo_(x)难熔高熵合金性能的影响

Influence of Mo content and pressure on properties of CrZrNbTiMo_(x) refractory high-entropy alloy calculated by first-principles

利用基于密度泛函理论的第一性原理方法研究Mo含量和压力对CrZrNbTiMo_(x)难熔高熵合金相结构、弹性常数和弹性模量的影响。计算了CrZrNbTiMo_(x)难熔高熵合金的混合焓(ΔH_(mix))、混合熵(ΔS_(mix))、原子半径差(δ)、价电子浓度(VEC)以及参数Ω。结果表明,CrZrNbTiMo_(x)难熔高熵合金主要以单一的BCC无序固溶体结构为主。随着Mo含量的增加,合金的晶格畸变不断减小,但力学性能稳定且始终以金属键结合。Mo的添加对合金的抗体积变形能力提升较大、对抗切应变能力及刚度影响较小,合金表现为韧性材料。在0~25 GPa压力作用下,CrZrNbTiMo_(0.6)合金表现出优异的相稳定性和力学稳定性,体弹性模量(B)增幅较小,剪切弹性模量(G)、杨氏模量(E)变化较小;泊松比μ及G/B计算结果表明合金为韧性材料。

First-principles method based on density functional theory was used to study the influence of Mo content and pressure on phase structure, elastic constants and elastic modulus of CrZrNbTiMo_(x)refractory high-entropy alloy. The mixing enthalpy(ΔH_(mix)), mixing entropy(ΔS_(mix)), atomic radius difference(δ), valence electron concentration(VEC) and parameter Ω of the alloy were calculated. The results show that the CrZrNbTiMo_(x)refractory high-entropy alloy is mainly composed of a single BCC disordered solid solution structure. With the increase of Mo content, the lattice distortion of the alloy is continuously reduced, but the mechanical properties are stable and the alloy is always bonded with metallic bonds. The addition of Mo greatly improves the volumetric deformation resistance of the alloy, but has less influence on shear strain resistance and stiffness, and the alloy behaves as a ductile material. Under the pressure of 0-25 GPa, the CrZrNbTiMo_(0.6)alloy exhibits excellent phase stability and mechanical stability, while the increment of bulk elastic modulus(B) is small, the variations of shear elastic modulus(G) and Young’s modulus(E) are small, and the Poisson’s ratio μ and G/B calculation results show that the alloy is a ductile material.