Constitutive Modeling of Cold Compaction and Sintering of Hardmetal

Abstract

Constitutive modeling and related numerical issues in conjunction with the macroscopic analysis and simulation of cold compaction and subsequent solid phase sintering of hard-metal are discussed. A key ingredient is the concept of sintering stress, which is derived as a thermodynamically consistent dissipative stress, based on a simplified microstructural arrangement with spherical pores. In order to account for the temperature effect on the rate-dependent response during the sintering phase, the concept of viscoplastic admissibility is employed as part of the model framework. A generic class of pressure-sensitive models is considered, and the particular model chosen for calibration is based on quasistatic and dynamic yield surfaces that are elliptic in the meridian planes of the stress space. Implicit integration is used for the pertinent evolution equations. The paper is concluded by a numerical investigation of the compaction and sintering of a specimen, whereby the model is calibrated using experimental data from free and uniaxially loaded sintering experiments (within a joint research project).