Finite element simulation of sintering process : Microscopic modelling of powder compacts and constitutive equation for sintering

Three-dimensional microscopic models of powder compacts for viscoplastic finite element analysis are developed to investigate the deformation behavior of powder particles during sintering. The repeating unit cells containing three types of pore with a regular arrangement are analyzed. Pore shrinkage due to surface tension during the intermediate stage of sintering is simulated. The volumetric strain rates of the unit cells are compared with that in a spherical shell model and the effect of the pore shape on the shrinkage rate and the sintering stress is discussed. A constitutive equation for sintering is proposed on the basis of the analyzed results. The sintering is described as the deformation process of viscous porous bodies under the action of the sintering stress. The proposed constitutive equation gives a good fit to the results obtained by experiment as well as the finite element analysis.