Preparation and mechanical properties of nickel particle reinforced alumina matrix composite
Nishikawa Tadahiro; Kawamura Yoshiyasu; Awaji Hideo
Abstract:Fracture toughness and other mechanical properties of alumina matrix composite reinforced with nickel particles were measured. Nickel/alumina composites up to 25 vol% of nickel contents were prepared by sintering in fine graphite powder bed under N2 gas atmosphere. Vibration was also applied during sintering to promote the dispersion of nickel particles in alumina matrix, using a high frequency apparatus. Decrease in Young's modulus and three point bending strength was observed with increasing nickel content. The fracture toughness, on the other hand, measured by SEVNB method increased with increasing nickel content. The fracture energy of composite was estimated by Griffith equation according to the observed fracture toughness and Young's modulus. The fracture energy increased in proportion to the total surface area of nickel particles comprised in the unit volume of composite. Increase in fracture energy corresponded to the formation of microcracks, which generated on nickel particles in the frontal process zone of composite. Decrease in bending strength was explained by the formation of large defects in composite, due to the large pore, decreasing of interparticle spacing or aggregation of nickel particles. Key Words:particle-reinforced ceramics, alumina, nickel, fracture energy, Griffith equation