论文标题
ZRC和HFC的温度依赖性机械性能来自第一原理
Temperature-dependent mechanical properties of ZrC and HfC from first principles
论文作者
论文摘要
为了深入了解升高温度对ZRC和HFC机械性能的影响，已经使用两种不同的方法（第一原则QUSI-Harmonic近似值和第一原理QUSI静态近似）系统地研究了这两个碳化物的温度依赖性弹性常数）。等气压c $ _ {11} $逐渐减小，在温度下，ZRC和HFC略微增加等entropic c $ _ {12} $。尽管ZRC和HFC的等enopic c $ _ {44} $对温度不敏感。在ZRC和HFC案例中，与QSA相比，从QHA计算出的温度依赖性C $ _ {11} $的下降更为明显。温度对弹性，泊松比，弹性各向异性，硬度和骨折韧性的影响。结果表明，从QHA估计的B，G和E的降解比在高温下QSA的降解更为严重。从室温到2500 K，b，g和e的理论减小（从QHA）为0.38 GPA $ \ cdot $ k $ k $^{ - 1} $，0.30 GPA $ \ cdot $ k $ k $ k $^{ - 1} $ gpa $ \ cdot $ k $^{ - 1} $，0.29 gpa $ \ cdot $ k $^{ - 1} $和0.30 gpa $ \ cdot $ k $ k $^{ - 1} $用于HFC。
In order to gain insight into the effect of elevated temperature on mechanical performance of ZrC and HfC, the temperature-dependent elastic constants of these two carbides have been systematically studied using two different methods (first-principles qusi-harmonic approximation and first-principles qusi-static approximation). Isoentropic C$_{11}$ gradually decrease and the isoentropic C$_{12}$ slightly increases for ZrC and HfC under temperature. While the isoentropic C$_{44}$ of both ZrC and HfC is insensitive to the temperature. In both ZrC and HfC cases, the decline of temperature-dependent C$_{11}$ calculated from QHA is more pronounced than from QSA. Temperature effects on modulus of elasticity, poisson's ratio, elastic anisotropy, hardness and fracture toughness are further explored and discussed. The results indicate that degradation of B, G and E estimated from QHA is more serious than these from QSA at high temperature. From room temperature to 2500 K, the theoretical decreasing slope (from QHA) of B, G, and E is 0.38 GPa$\cdot$K$^{-1}$, 0.30 GPa$\cdot$K$^{-1}$, and 0.32 GPa$\cdot$K$^{-1}$ for ZrC and 0.33 GPa$\cdot$K$^{-1}$, 0.29 GPa$\cdot$K$^{-1}$, and 0.30 GPa$\cdot$K$^{-1}$ for HfC.
