Particle curvature effects on microstructural evolution during solid-state sintering: phenomenological insights from phase-field simulations

Abstract

Local curvatures have a profound influence on sintered microstructure. Here, using phase-field simulations, particle curvature effects were phenomenologically investigated by using geometrical configurations of two, three, and four particles, and by systematically varying particle curvatures. Some geometries, involving two, three and four particles, exhibited the expected smooth neck-length evolution, where the maximum neck length was determined by grain boundary (GB) energy ($\gamma _{GB}$) rather than surface energy ($\gamma _{S}$). In contrast, triangular arrangement of particles with unequal radii manifested a secondary necking event in form of a step during neck evolution. The secondary necking event coincided with internal pore collapse, and only specific range of particle radius ratios manifested such a mechanism. $\gamma _{S}$ played a dominant role in triggering the secondary necking event, while $\gamma _{GB}$ determined the remnant microstructure. Broadly, the geometries employed here allow us to computationally examine the sintering of particles that display wide variation in shapes and size distributions.