Fabrication of AZ91D/SiCp composites by mechanical milling of magnesium alloy chips and spark plasma sintering in a semi-solid regime

ABSTRACT In the present study, the capability of spark plasma sintering (SPS) in a semi-solid regime to produce AZ91D/SiCp composites, prepared by mechanical milling (MM), was investigated. An SPS process was used to densify AZ91D/SiCp composite powders by heating them to a semi-solid temperature of 497°C or 516°C, at a heating rate, holding time and pressure of 50 °C/min, 1 min and 40 MPa, respectively. In preparing the requisite powders, MM was used as an effective recycling method to prevent excessive consumption of energy and raw materials while converting magnesium alloy chips into powder in a planetary ball mill. The simultaneous effects of milling parameters (time and ball-to-powder weight ratio (BPRs)) on the MM powder were investigated by FESEM and PSA. Mechanical alloying (MA) of the milled powder with 40 wt% ？2 μm SiC and characterization of the obtained powder by OM and PSA were also carried out. The phase compositions of the powder and sintered samples were analyzed by XRD. The microstructure, density, hardness and compressive strength of the sintered samples were also studied. The results show that composites with few porosities and good mechanical properties were prepared by SPS in a semi-solid regime