Effects of La and Ce on microstructure and properties of SiC/Al composites

SiC/Al composites were prepared using a pressure-less infiltration technique with silicon carbide powders and aluminum alloys (containing 3%Mg and 3%Mg-0.5%(La + Ce), respectively) as the main raw materials. The effects of La and Ce on the phase composition, microstructure, mechanical and thermal properties of SiC/Al composites were investigated. The density of a SiC/Al composite was increased, and the grains of the aluminum alloy matrix were refined through the addition of La-Ce, which is beneficial to improve the mechanical and thermal properties. The flexural strength of the SiC/Al composite prepared through the addition of La-Ce was 372.33 +/- 12.37 MPa, the fracture toughness was 8.56 +/- 0.24 MPa m(1/2), and the thermal conductivity was 176.76 W/(m.K). Compared with the SiC/Al composites without La-Ce, the flexural strength, fracture toughness, and the thermal conductivity were increased by 12.4%, 10.1%, and 10.5%, respectively.