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 combin ing 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 pa per. The crack growth toughness has also been related to fundamental m icrostructural properties of these composites. A critical ratio of You ng's modulus to flow stress to enable stable crack growth has been est ablished. Suitable suggestions for tailoring the microstructure to opt imize crack growth toughness have been discussed.