钼在Cr_2AlC中合金化行为的第一性原理研究

Study on First-principles of Alloying Behavior of Mo in Cr_2AlC Compounds

采用基于密度泛函理论的第一性原理赝势平面波方法计算了Cr2AlC的M位置的固溶体Cr4-xMoxAl2C2的相稳定性及电子结构。通过对Cr4-xMoxAl2C2的弹性常数、形成能和结合能的计算分析,得到Cr4-xMoxAl2C2在力学和热力学上都是稳定的,从而确定Cr4-xMoxAl2C2是结构稳定的化合物。另外,还对Cr4-xMoxAl2C2的体模量、剪切模量和态密度进行了计算与分析。通过对B/G的分析发现,Cr4-xMoxAl2C2表现出脆性,但随Mo含量的增加,Cr4-xMoxAl2C2的韧性逐渐提高。

Using density functional theory based on first-principles plane-wave pseudopotential method, the stability and electronic structure of Cr_4-χMoχAl2C2 was calculated. The calculated elastic constants, formation energy and cohesive energy show that Cr_4-χMoχAl2C2 are mechanically and energetically stable. Moreover, the bulk modulus, shear modulus and density of states of Cr_4-χMoχAl2C2 are calculated. By calculating the ratio of bulk modulus to shear modulus （the value of B/G）, it can be obtained that Cr_4-χMoχAl2C2 is brittle, but the increase of Mo content can decrease the brittleness.