EFFECT OF PARTICLE-SIZE ON FRACTURE-TOUGHNESS IN METAL-MATRIX COMPOSITES

A model is presented which describes the relationship of plane strain fracture toughness (K-1C) and yield strength of particle-reinforced me tal matrix composites. Tensile tests and fracture toughness tests were conducted on five aluminum 2014-T6 metal matrix composites reinforced with 10 and 15 volume percent of B4C, Al2O3, and SiC particles of dif ferent sizes. Experimental results showed that larger reinforcement pa rticles enhance fracture toughness. A model was established by proposi ng that the plastic zone at the tip of particle cracks is of the order of the inter-particle spacing. This model predicted the exact trend f rom the experimental results.