Hydrostatic stresses and their effect on the macroflow behavior and microfracture mechanism of two-phase alloys

Abstract

The aspects of the hydrostatic pressure and tension stresses developed as a result of the interaction between hard and soft phases to maintain compatibility are represented for two-phase alloys with different microstructures. It has been theoretically proved that the stress triaxiality, defined as the ratio of the hydrostatic stress to the effective stress (Σ H /Σ e ), causes hardening or softening of the component phases. The average hydrostatic tension and pressure stresses in soft and hard phases developed during monotonic loading make the soft phase harden and hard phase soften. The extent of the hardening and softening increases with the strength ratio of the hard phase to soft phase and the size of the particles and decreasing the phase content. The hardening or softening effect of thein situ constituents has important influence on the flow stress of the composites and is one of the important reasons for deviation from the law of mixtures in prediction of the flow stress of composites based on that of the component phases in bulk. The stress triaxiality distributions in microstructure scale also provide an explicit physical picture of the microfracture mechanisms of the two-phase alloys.