Multi-phase-field modeling of sintering applicable to solid-state and liquid-phase sintering in multiphase and multicomponent systems

A thorough understanding and control of the microstructural evolution during sintering is essential for improving the properties of various sintered materials. In this study, a new multi-phase-field (MPF) model of sintering that applies to both solid-state sintering (SSS) and liquid-phase sintering (LPS) in multiphase and multicomponent systems was developed. The MPF model incorporates the advection term to account for the rigid-body motion (RBM) of the sintered particles. Moreover, the MPF model provides thermodynamically reasonable results of phase transformation and solute diffusion when coupled with a thermodynamic database. The effect of incorporating the RBM was validated by evaluating the neck growth and densification rates obtained from the simulation results of SSS. The MPF simulation results of the initial stage of LPS demonstrated that the a) MPF model could reproduce the densification behavior, which depends on the phase transformation between the solid and liquid phases, and b) RBM is an important factor in reproducing the densification behavior. A long-term MPF simulation of the LPS also demonstrated that the microstructural evolution, including three densification-related mechanisms—contact flattening, Ostwald ripening, and solid-state bonding—could be analyzed from the initial to final stages of the LPS. This study is expected to advance the sintering process applicable to multiphase and multicomponent systems.