Microstructure and tensile properties of magnesium matrix composite: effected by volume fraction of micron SiCp

In this paper, three volume fractions (2, 5 and 10%) of 10 mu m SiCp/AZ91 magnesium matrix composite were fabricated by stir casting. The as cast ingots were forged at 420 degrees C with 50% reduction first and then extruded at 370 degrees C with a ratio of 16 : 1. The results show that the grain is refined significantly after hot deformation process, which results in the enhancement of tensile properties. The volume fraction of micrometre SiCp has significant effect on grain size by influencing dynamic recrystallisation of magnesium. By the increase in particle volume fraction, the grain size decreases, the dislocation density increases and the load transfer effect is strengthened, thus leading to the significant improvement of yield strength. The ultimate tensile strength of the composite increases with the increase in particle volume fraction due to the improved deformation uniformity of matrix and the enhanced hindering effect on crack propagation.