Dynamic Recrystallization Behavior of Bimodal Size SiCpReinforced Mg Matrix Composite during Hot Deformation

The (submicron + micron) bimodal size SiCp-reinforced Mg matrix composite was compressed at the temperature of 270-420 °C and strain rate of 0.001-1 s^-1. Then, dynamic recrystallization (DRX) behavior of the composite was investigated by thermodynamic method and verified by microstructure analysis. Results illustrated that the composite possess the lower critical strain and higher DRX ratio as compared to monolithic Mg alloys during hot deformation process. The predicted DRX ratio increased with the proceeding of compression, which was well consistent with the experimental value. Results from thermodynamic calculation suggested that the occurrence of DRX could be promoted by SiCp, which would be further proved by microstructure analysis. Formation of particle deformation zone around micron SiCp played a significant role in promoting DRX nucleation. Nevertheless, the distribution of submicron SiCp was increasingly uniform with the proceeding of compression, which could fully restrain grain growth. Therefore, the corporate effects of micron and submicron SiCp on DRX contributed to the improvement of DRXed ratio and the refinement of grain size for the composite during compression process.