A MACROSCOPIC MODEL FOR PLASTIC-FLOW IN METAL-MATRIX COMPOSITES

A micromechanically based continuum model is developed to analyze the enhancement of plastic properties of particulate-reinforced metal-matr ix composites over matrix materials. The composite is idealized as uni formly distributed periodic arrays of unit cells. Each unit cell consi sts of a rigid inclusion surrounded by a plastically deforming materia l. An energy method is adopted to obtain the overall constitutive rela tion for the composite on the basis of the local nonuniform deformatio n fields. Effects of particle volume fractions and shapes (e.g. whiske rs, discs, etc.) as well as the matrix properties on the flow properti es of the composite are obtained. The results are in good agreement wi th experimental observations and finite element analyses found in the literature. An explicit expression is also proposed, providing a means for evaluating various factors affecting the strength of composites.