Molecular Dynamics Simulation of Uniaxial Tensile Mechanical Properties and Failure Mechanisms of MgAl2O4 Spinel

Abstract

This study employs the molecular dynamics method to examine the tensile mechanical properties and failure mechanism of MgAl2O4 spinel along [001] orientation. The results indicate that the mechanical properties of MgAl2O4 are sensitive to temperature. Young's modulus and ultimate tensile strength (UTS) of MgAl2O4 exhibit a linear decrease with increasing temperature from 100 to 2100 K. Specifically, Young's modulus decreases from 237.1 to 154.9 GPa, while the UTS decreases from 23.9 to 11.5 GPa. The failure mechanism of MgAl2O4 under uniaxial tensile loading is a brittle fracture induced by point defects. The propagation of microcracks in MgAl2O4 single crystal during tension is related to the slip band. The temperature does not have a significant effect on the direction of microcrack propagation, but it influences the crack expansion rate. In addition, the effect of strain rate on the mechanical properties of MgAl2O4 has been explored. In the range of 5 × 108 to 2 × 1010 s−1, the strain rate has almost no effect on the elastic modulus and the crack propagation direction and has little influence on the UTS. However, high strain rates delay the initiation of MgAl2O4 cracking.