The influence of SiC–Al2O3 reinforcements on the deformation and fracture mechanism of thixomolded Mg-based composite.

The thixomolding technology offers distinct advantages for producing magnesium matrix composites with intricate geometries. This study explores the effects of incorporating hybrid SiC–Al2O3 particles on the microstructure, deformation, fracture, and mechanical properties of a thixomolded Mg–10Zn alloy. The composite exhibits a homogeneous distribution of Al2O3 and SiC particles within the matrix. The addition of SiC–Al2O3 reinforcements helps reduce the content of primary α -Mg solid and refine the microstructure. The composite demonstrates a yield strength of 186 MPa, an elastic modulus of 48.6 GPa, and a respectable elongation of 6.8%. The digital image correlation measurement was performed at the sample scale, unveiling overall deformation characteristics. Crystal plasticity finite element method was employed for high-fidelity microstructure, showcasing mesoscale deformation feature such as the deformation mechanism of grains adjacent to reinforcements. It was found that SiC–Al2O3 particles prevent the formation of large shear band, benefiting the ductility of the material. The post-mortem analysis using scanning electron microscope near the fracture position reveals micro-cracks inside the SiC particles. Notably, the SiC/Mg interface shows no signs of cracking, while some Al2O3/Mg interfaces are separated. Reinforcement cracking is correlated to the stress it withstands, and the mesoscale deformation analysis reveals that the reinforcement stress is increased when non-basal slip in grains adjacent to the reinforcement becomes difficult to be activated. This work serves as an example for developing Mg matrix composites through the thixomolding process. The findings of this study provide valuable insights for the design of high-performance thixomolded Mg-based composites [ABSTRACT FROM AUTHOR]