Search

International audience; This paper presents a numerical model that is capable of simulating microstructural evolution during simple solid-state sintering of a complex 3D powder particle compact. This model, a Potts kinetic Monte Carlo model, is a true mesoscale model that can simulate a large number of particles while resolving microstructural features such as particles, necks, pores and more in detail. Furthermore, it is shown that this model can simulate all the stages of sintering from the initial particle contact to neck growth with open, percolating porosity to closed isolated pores seamlessly. The various kinetic processes that lead to densification and other microstructural changes are shown to be simulated correctly. The model is demonstrated by comparing the microstructural evolution resulting from simulation to experimental results, namely 3D microtomographic images obtained from synchrotron radiation of a Cu-powder compact while it was sintering. For quantitative comparison, we extrapolated a grain structure into the simple microtomographic image that consists of mass distribution only.

We present a model that describes anisotropic shrinkage during sintering in a powder compact of aligned, elongated particles by deriving the anisotropic sintering stress and the anisotropic generalized viscosity as a function of material and geometric parameters. The powder compact consists of elongated particles, which are perfectly aligned and simply packed with elliptical pores at all the quadra-junctions between the particles. The model considers mass transport by grain boundary diffusion and surface diffusion. Shrinkage rates are calculated for a variety of geometries and are compared to kinetic Monte Carlo simulations.

This paper discusses in detail the development of a numerical model capable of simulating microstructural evolution and macroscopic deformation during sintering of complex powder compacts. The model based on the kinetic Monte Carlo (Potts) approach simulates grain growth, vacancy diffusion, and pore annihilation at grain boundaries, which is responsible for densification. Results of 2D simulations for perfect close-packed and random starting configurations are presented and discussed. The microstructural evolution is used to obtain the sintering stress––the macroscopic stress that is equivalent to the microstructural driving force for deformation.

An experimental validation of a 3D kinetic, Monte Carlo model for simulation of microstructural evolution during solid state sintering will be presented. The model – a statistical mechanical model, which can simulate curvature-driven grain growth, pore migration, and vacancy formation, diffusion and annihilation – is validated by comparing microstructural evolution obtained experimentally for a copper powder compact. The 3D microstructural evolution of copper powder particles sintering was imaged in-situ by microtomography. The images show particles with internal porosity percolating through the particles. Microstructural features – e.g., neck formation and growth – from the experimental images as well as the overall densification rates are compared to the simulations.