Atomistic Migration Mechanisms of [1210] Symmetric Tilt Grain Boundaries in Magnesium

Grain boundary (GB) is an important microstructure and plays a vital role in the mechanical properties of polycrystalline materials by GB migration and sliding.In this work, molecular dynamic (MD) simulations were performed to investigate the migration mechanisms of [12 " 10] symmetric tilt grain boundaries (STGBs) in magnesium.A total of 15 STGBs with the rotation angle θ from 0° to 90° were studied under a pure shear loading.The results show that the GB migration mechanisms are significantly influenced by the GB structure.For small angle STGBs (θ<28°), the GB migration is mediated by twin nucleation from GB and subsequent twin growth.For large angle STGBs (θ>83°), the GB migration is achieved by the glide of GB dislocations.The medium angle STGBs (28°<θ<83°), which are the majority of studied STGBs, were observed to be transformed into twin boundary (TB) by emitting lattice dislocations/stacking faults (SFs) during migration.The migration mechanisms for medium angle STGBs can be explained by two rules: GB decomposition and emission of lattice dislocations/SFs.This work provides atomic mechanisms on the GB migration, which are important for understanding the GB behaviors and mechanical properties in magnesium.