Elastic and plastic properties of powder materials: a continuum model

A continuum model based on the physical hypotheses of the discrete contact model is developed to describe the elastic and plastic properties of isotropic powder materials, taking into account the inhomogeneous deformation of the solid phase. The localization of elastic and plastic deformation is described by hypothesizing that deformable and nondeformable volumes form in the solid phase and that the resistance to deformation is associated only with the deformable volume. An analytical dependence of the deformable volume on the density of powder material is provided. The proposed model ensures high-accuracy fit to the experimental compaction curves at the stages of interparticle slip and plastic deformation of particles. At the beginning of plastic deformation, a particle is regarded as a cast one already plastically deformed and hardened to the level of the effective yield strength of the solid phase. The particle is further hardened as a cold-worked cast material is. Good agreement is reached between calculated and experimental data on the elastic moduli and plastic compaction of powders during isostatic pressing and deposition in a high-pressure chamber.