Effects of (micron plus submicron plus nano) multisized SiC particles on microstructure and mechanical properties of magnesium matrix composites

Many interesting studies on composites with nano or submicron SiCp have been performed since the size advantages of fine SiC particles. However, it is extremely hard to disperse fine particles in metal melts due to their poor wettability and large surface-to-volume ratio, especially the fabrication of composites with multisized SiCp (5 mu m, 0.5 mu m, and approximate to 60nm) is very difficult. The use of multisized reinforcements is required to solve the dispersion problem. The stir casting technology and hot extrusion method could be used to disperse the multisized SiCp in the matrix. The effects of multisized SiCp on the dynamic recrystallization behavior of the composites are discussed. The large-scale dynamic recrystallization caused by adding multisized SiCp results in a fine matrix microstructure. Compared with the as-accepted AZ31B alloy (YS: 195MPa, UTS: 277MPa), the yield strength and ultimate tensile strength of the AZ31B/SiCp/n-1+S-4+5-10 composite were enhanced to 73.8 and 44.8%, respectively. The better tensile properties were attributed to the uniform distribution of reinforcement, strengthening effect of multisized SiCp, and grain refinement of magnesium matrix.