The first-principles study of the mechanical, electronic and thermodynamic properties of Zr(Hf)-Cr(Mo)-Si silicide

Based on the density functional theory, the mechanical properties and density of states of four kinds of silicide were predicted. HfMoSi maintains the highest strength, but its plasticity is poor. The electrons around the Si atoms are highly localized and form covalent bonds with the transition metal atoms. The quasi-static approximation was used to predict the elastic constants and modulus of silicide in the range of 0-1800 K. With the increase of temperature, the volume expansion leads to the decrease of interatomic bonding and the decrease of silicide strength. The anisotropy index show that all the silicide are anisotropic materials, and their anisotropy is the strongest in HfCiSi. The quasi-harmonic Debye model predicts that the Debye temperature of silicide will decrease with temperature, which has a certain influence on the mechanical behavior of the material. The results of the minimum thermal conductivity show that ZrCrSi has higher thermal conductivity.