A MICROMECHANICAL MODEL FOR CRACK-GROWTH RESISTANCE OF PARTICULATE-REINFORCED METAL-MATRIX COMPOSITES

Particulate-reinforced metal-matrix composites are being developed to satisfy the need for high stiffness, high strength materials by combining the beneficial properties of both metals and ceramics. The use of such composites as structural members necessitates an understanding of their damage tolerance. A model relating the crack growth resistance to initiation toughness and tensile properties is developed in this paper. The crack growth toughness has also been related to fundamental microstructural properties of these composites. A critical ratio of Young's modulus to flow stress to enable stable crack growth has been established. Suitable suggestions for tailoring the microstructure to optimize crack growth toughness have been discussed.