Microstructural Evolution and Anisotropic Shrinkage in Constrained Sintering and Sinter Forging

The microstructures of sintering bodies become anisotropic in constrained sintering of a thin film on rigid substrate, as well as in stress-assisted densifications such as sinter forging and hot pressing. The deformation and the stress states in the body have been described by general constitutive equations using sintering stress tensor and viscosity tensor. These macroscopic quantities were determined from local microstructure and microscopic kinetics for the special case of face-centered tetragonal structure. The simulation results were applied to the cases of sinter forging and constrained sintering and qualitatively compared to the experimental results available in the literature. This model is able to predict both the evolution of the anisotropic microstructure during sintering, and also the effect of the local micro-structure on anisotropic shrinkage.