空位对Hf-Ta-C体系的结构、力学性质及电子性质影响的第一性原理研究

本研究理论预测了三元Hf-Ta-C空位有序结构以及空位对力学性质的影响.采用第一性原理进化晶体结构预测软件USPEX,预测得到了5种热力学稳定和3种亚稳的(Hf,Ta)C1–x空位有序结构,这些结构都属于岩盐结构.采用第一性原理方法,计算了(Hf,Ta)C1–x空位有序结构的力学性质,并分析了力学性质随空位浓度的变化....

Vacancy on Structures,Mechanical and Electronic Properties of Ternary Hf-Ta-C System: a First-principles Study

In this study,the first-principles method was used to predict the vacancy ordered structures of ternary Hf-Ta-C system and the effect of vacancy on its mechanical properties.Crystal structure of(Hf,Ta)C_1-x under ambient pressure were predicted by first-principles evolutionary using USPEX software.This calculation found 5 stable and 3 metastable vacancy ordered structures which all share the rock-salt structure.Then,mechanical properties of(Hf,Ta)C_1-x vacancy ordered structures were calculated by the first-principles method,and change of mechanical properties with the concentration of vacancy was analyzed.They all showed high bulk modulus,shear modulus,elastic modulus,and Vickers hardness.Their moduli and hardness decreased with the increase of the concentration of vacancy at the same Hf/Ta ratio.Finally,their electronic density of states are calculated,revealing that their chemical bonding is a mixture of strong covalence and weak metallic.Data from this study are promising for understanding vacancy ordered structures,mechanical properties and applications of Hf-Ta-C system.