Thermal stress and strain in a metal matrix

The stresses and strains, induced by coefficient of thermal expansion (CTE) mismatch, are analyzed for a metal matrix composite (MMC) with a spherical reinforcement particle. The spherical reinforcement particle is found to be in a hydrostatic stress state and remains in the elastic state. The stresses and strains are largest, and plastic deformation occurs in the matrix adjacent to the reinforcement particle. Accordingly, the reinforcement particle/matrix interface becomes a potential crack initiation site under thermal cycling. The critical internal pressure for plastic deformation is less than two-thirds of the yield stress of the matrix material and decreases with increasing range of thermal cycle.