Microstructure evolution of AZ80 magnesium alloy in semi-solid compression by molecular dynamics simulation

Abstract

Molecular dynamics (MD) simulation and experiments were carried out in this work to probe the microstructure evolution in the semi-solid compression (SSC) of AZ80 magnesium alloy. The liquid phase flow, stress fluctuations, grain refinement, dislocation generation, and texture evolution were discussed. Results indicate that the liquid phase was squeezed out along the radial direction prior the solid phase at the beginning of compression. Stress-strain curve represented obvious fluctuation at lower strain rates. That resulted from stress reduction caused by more liquid evolving with a lower strain rate at an elevated temperature. Plastic deformation was detected in grains and the dislocations of 1/3<11¯00> dominated the deformation, while and 1/3<12¯10> just been activated at the beginning of SSC process. The results of EBSD showed the grains size was refined into about 38.8 μm from 92.3 μm after SSC process. During the process, grain refinement resulted in the increase of low-angle grain boundaries (LAGBs), and a strong (0001) basal plane texture evolved at the end. The higher the strain rates, the stronger the texture.