Phase field modeling of sintering: Role of grain orientation and anisotropic properties

The influence of anisotropic properties of powder particles on microstructural evolution during solid-state sintering processes is analyzed. Two types of anisotropy studied in the current work are direction-dependent interface diffusion anisotropy, and grain orientation dependent grain boundary energy anisotropy. A phase field modeling approach is utilized to assess how the individual anisotropic characteristics influence morphological changes during sintering. In addition, a novel approach for updating grain orientation after rigid-body rotation of particles during powder compaction accompanying the sintering process is developed. It is observed that conventional isotropic microstructural analysis over-simplifies the material behavior and demonstrates faster microstructural evolution. Direction-dependent diffusion produces gradual shape change of the particles by mass transfer from high curvature region to low curvature region along the particle surface, and delays the onset of the grain growth process. Depending on the grain boundary misorientation and inclination, anisotropic grain boundary energy may induce faster or slower grain boundary migration rate. Orientation update during the process plays a critical role in the consolidation kinetics, as well as in the final microstructural configuration. Variation in grain orientation and its evolution during the sintering process can produce different grain morphologies for the same initial condition.