高圧鋳造法および粉末冶金法によるSiCウィスカー強化マグネシウム複合材料の組織と機械的特性

抄録

SiC whisker reinforced composites with a pure magnesium matrix were fabricated by two different processing routes, high pressure casting and powder metallurgy. The structures and mechanical properties were compared on the obtained composites after hot extrusion. The extruded composites by the P/M process showed slightly higher average aspect ratio and less uniform distribution of SiC whiskers than those by high pressure casting. Increases in hardness and elastic modulus with the whisker V_f were observed to be the same for both composites. However, the P/M composites showed much less increases in tensile strength than those by high pressure casting. In the P/M composites, decohesion at the matrix-reinforcement interface occurred under tensile load. No chemical reaction was observed between the matrix and SiC whiskers in P/M composites, whereas surface oxide of whiskers reacted with magnesium melt in high pressure cast composites. Such an interface reaction is necessary for strong matrix-reinforcement cohesion, and thus the P/M process is considered to be unsuitable for fabrication of SiCw/Mg composites.