Dudunov V. The behaviour of powders and composites under simple and complex loading and at the stage preceding the failure

Powder metallurgy processes targeted at shape formation and densification of powder materials containing hard inclusions are considered. The main purpose of the consideration - is the formulation of the failure criteria under the plastic flow such materials sensitive to inclusions and their interaction with powder matrix. The micromechanical approach has been used to formulate the extended expressions for materials functions in plasticity theory of composite with porous matrix. Apart the dependence between the limit deformation and inclusion size for particles subjection is obtained. The effect of material hardening on subjection is estimated. As result the model of plastic straining for the given type of composite is formulated. Using this model and knowledge about the physical stability of deformation the theory of fracture for materials considered here is formulated. It is used for the analysis of shape formation and densification in powder technology. Obtained results are employed to optimizethe content of composite as well as to avoid loading paths, where the failure is expected.