Effects of Solution and Aging Treatment on Microstructure and Properties of Semi-solid Extruded SIC/AZ91D Alloy

In order to obtain the magnesium matrix composites with good mechanical properties, the semi-solid 15wt% SiC/AZ91D billet with 10 gm in length was prepared by the near-liquidus heat-holding method and later extruded to get the magnesium matrix composites. Solution treatment at 415 degrees C for 24 h (T4) was conducted, followed by further aging treatment at 220 degrees C for 8 h (T6). The results show that during the solution and aging treatments, Mg17Al12 phases at the grain boundary dissolve, and the secondary-precipitated phases appearing in grains become layered and spheroidized gradually. The magnesium matrix composites 15wt%SiC/AZ91D after T6 treatment show better integrated mechanical properties when compared with those of the composites before T6 treatment. The tensile strength, yield strength, elongation, and hardness reach 242 MPa, 204 MPa, 2.3% and 1322 MPa, respectively.