Abstract
Mo-Si-Al alloy and Mo-Si-Al/SiC composite were fabricated by the powder metallurgical process from a novel Mo-Si-Al prealloyed powder, and their microstructure and mechanical properties were evaluated. The Mo-Si-Al and Mo-Si-Al/15 vol%SiC mixed powders were hot-pressed in an argon atmosphere. XRD analyses revealed that Mo-Si-Al/SiC composites were composed of MoSi2 (tetragonal, Cllσ structure), Mo(Si, Al)2 (hexagonal, C40 structure), a-Al2O3, Mo ?? 5Si3C ?? 1 and β-SiC. Almost no glassy SiO2 phase was found in Mo-Si-Al and Mo-Si-Al/SiC systems contrary to MoSi2 and MoSi2/SiC. The formation of α-Al2O3 was attributed to the predominant oxidation of aluminum at the surface of the Mo-Si-Al prealloyed powder. Mo-Si-Al based systems showed the better high-temperature strength mainly due to the elimination of glassy SiO2 and the crystallographical change from t-MoSi2 to h-Mo(Si, Al)2. Incorporation of fine SiC particles enabled to control microstructure and then to enhance mechanical properties.
