Mechanical performance analysis of WZ-AlN: Quantitative study on elastic properties, generalized stacking fault energy and doping effects

Abstract

The generalized stacking fault energy (GSFE) has a significant impact on the mechanical properties of materials, especially on the plastic deformation ability of materials. In this paper, based on the density functional theory (DFT), we calculate the GSFE on the basal-plane {0001} and the prismatic-plane {10$\overline{1}$0} of wz-AlN (wurtzite aluminum nitride). Meanwhile, the GSFE is also calculated when the Al atom is substitutionally doped with group-Ⅲ elements B, Ga, In, Tl, and 5d transition-metal elements Hg, Ir, Os, Re. Research indicates that in wz-AlN, except for the <10$\overline{1}$0> direction of the basal-plane {0001}, the unstable stacking fault energy γ_us of the Shuffle type is smaller than that of the Glide type. Due to the existence of type-II stacking fault, among all the slip systems, the unstable stacking fault energy γ_us of the basal-plane {0001} Glide type along the <10$\overline{1}$0> direction is the minimum. Consequently, the material exhibits superior plasticity when deformation occurs along this specific direction. Among the group-Ⅲ element dopings, Tl atom has the most significant enhancement effect on the plastic deformation ability of wz-AlN. Among the 5d transition-metal elements, Hg atom has the best enhancement effect on the plastic deformation ability of wz-AlN. Meanwhile, it is found that the greater the difference between the radius of the doping atom and that of the base atom, the better the effect on enhancing the plastic deformation ability of the material.