ＳｉＣウィスカ強化アルミニウム合金複合材料の機械的性質に及ぼすウィスカ体積率の影響

Abstract

SiC whisker reinforced aluminum alloy composites with whisker volume fraction (Vf) ranging from 0 to 40% were fabricated by a powder metallurgical method. In a low Vf range, the ultimate tensile strength increases proportionally with the increase of Vf and agrees satisfactorily with the value calculated from Kelly and Tyson's equation. In a high Vf range, however, the increasing rate of strength becomes smaller than the theoretical value due to the decrease in ductility of composites. This deviation from the proportional line takes place at a lower Vf and the decrease in strength is also observed in higher strength aluminum alloy matrix composites. At elevated temperatures, the tensile strength follows the proportional relationship with the Vf to a higher Vf range due to the improvement in ductility. The elastic modulus increases as the Vf increases and is in good agreement with the value calculated from Cox's equation, assuming that the elastic modulus of whiskers is 43, 000kgf/mm2. The whisker orientation factors of three dimensional random array composites for the strength and the elastic modulus are determined experimentally as 0.38 and 0.68, respectively.