Inhibition of grain growth during the final stage of multi-stage spark plasma sintering of oxide ceramics

Previously, we reported the efficacy of multi-stage spark plasma sintering (SPS) to produce a uniform microstructure and superior properties in ultrafine-grained ceramics. Fundamentally, it is important to assess the microstructure development during the final stage of sintering. With a designed set of exploratory experiments on oxide ceramics, this work demonstrates how grain growth is significantly inhibited during the multistage SPS process. The results are explained in terms of competition between grain boundary diffusion and grain boundary migration.