A study on the mechanical properties of polycrystalline aluminum nitride based on molecular dynamics simulation

Abstract

In the actual preparation process of surface acoustic devices and power devices, AlN mostly has a polycrystalline structure, and the average grain size has a significant effect on its physical properties. In addition, owing to its high temperature resistance, AlN has a wide operating temperature range. Therefore, in order to reveal the effect of average grain size and temperature on the variation of microscopic mechanical properties of polycrystalline AlN, the molecular dynamics method was adopted to study the tensile process of polycrystalline AlN. The results indicated that the elastic modulus and lattice phase transition of polycrystalline AlN are closely related to the average grain size and loading temperature. The larger the average grain size, the higher the elastic modulus. As an important location for crack initiation and propagation, grain boundary plays an important role in the occurrence of high strain failure and lattice phase transition in the system under loading. In addition, the brittle fracture process of polycrystalline AlN is changed to a certain extent with the increase of temperature, and the fracture toughness is gradually enhanced.