Microstructures and performances of pressureless sintered MoSi2-Al2O3 composites

MoSi2-Al2O3 composites with various volume fractions of Al2O3 from 0 to 40 vol% were fabricated by pressureless sintering at 1550 ℃. MoSi2 powder was prepared by silicothermic reduction of MoS2. Microstructure, mechanical properties, electrical resistivity and oxidation behavior of composites were experimentally examined to investigate the influence of Al2O3 addition. The results demonstrated that proper introduction of Al2O3 contributed to improving the oxidation resistance and mechanical properties. Among them, MoSi2-20 vol%Al2O3 composite presented excellent comprehensive properties and oxidation resistance. The oxide scale consisting of SiO2 and Al2O3 was formed on the substrate and effectively prevented the inward diffusion of oxygen.