Discrete Element Method Sintering Simulation: A Grain-Scale Simulation Approach

The sintering models described in previous chapters consider only a limited number of particles or analytical analyses of sintering, without a close connection to the sintering of large parts. While the previous chapter addressed the serious issues that have to be considered in the “real world” of sintering, great advances have been made on the simulations of sintering of real complex shapes. This chapter addresses simulations based on the Discrete Element Method (DEM), a promising new technique to model sintering by directly taking the microstructure into account. Each grain is modeled as an individual particle which interacts with its neighbors by given force laws that depend on the diffusion mechanisms. In this chapter the grain-scale simulation model is explained in detail and it is shown how it can be used to model sintering of both standard and nanoparticle powders. By directly considering effects like rearrangement, crack formation and anisotropy development new insights into many sintering processes are gained. Especially the influence of grain rearrangement, which cannot directly be considered with traditional continuum mechanical approaches, is studied in detail. As a demonstration example constrained sintering of inkjet printed silver powders is given. Since the method is still relatively new, not all sintering mechanisms are fully considered yet. It is shown how grain coarsening models could be improved by considering the growth process on the grain scale as well.