Dynamic recrystallization behavior during hot deformation and mechanical properties of 0.2 μm SiCp reinforced Mg matrix composite

In this paper, 0.2 μm SiCp/AZ91 composite was fabricated by stir casting technology. The influence of fine (<1 μm) particles on the dynamic recrystallization (DRX) behavior of AZ91 matrix was investigated by researching the microstructure evolution of 0.2 μm 1 vol% SiCp/AZ91 composite during the hot extrusion process. Results showed that the DRXed ratio of AZ91 matrix increased as well as the average size of DRXed grains reduced due to the addition of fine particles. The SiCp could not only pin dislocation, but also was helpful to generate dislocations owing to the deformation mismatch between matrix and particles, thus causing the increase of dislocation density around SiCp, which was benefit to stimulate DRX nucleation. Meanwhile, the growth of DRXed grains was suppressed in the following deformation process due to the pinning effect of fine particles on grain boundaries. Thus, the fine particles had significant effect on stimulating DRXed nucleation and refining grain size. The yield strength and ultimate tensile strength of the as-deformed 0.2 μm 1 vol% SiCp/AZ91 composite are 275 and 335 MPa, respectively, which are mainly attributed to the grain refinement, basal plane texture and uniform particle distribution induced by hot deformation.