Effect of MoSi2 and Nb reinforcements on mechanical properties of Al2O3 matrix composites

Author： Chakraborty A. Kamat S.V. Mitra R. Ray K.K.

ISSN： 0022-2461

Source： Journal of Materials Science, Vol.35, Iss.15, 2000-08, pp. : 3827-3835

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Abstract

The room temperature mechanical properties of Al_2O_3 composites reinforced with 25 vol% of either MoSi_2 or Nb particulates were investigated. It was found that addition of Nb particles resulted in a reduction in the elastic modulus, but caused a significant increase in both flexural strength and fracture toughness. On the other hand, the addition of MoSi_2 particles resulted in only a marginal decrease in elastic modulus and marginal increase in both flexural strength and fracture toughness. The elastic modulus results were explained on the basis of Tsai - Halpin model. For both the composites, the increase in flexural strength was attributed to the grain refinement of the Al_2O_3 matrix as well as the load transfer to the reinforcement particles. The marginal increase in fracture toughness in Al_2O_3 / MoSi_2 composites was attributed to crack deflection, whereas the threefold increase in fracture toughness in Al_2O_3 / Nb composites was attributed to crack blunting and bridging.