ZrO₂ PARTICLE GROWTH MECHANISM AND TOUGHENING MECHANISM OF ZrO₂/β″-Al₂O₃

This paper discusses the particle growth mechanism of intergranular ZrO₂ particles of t-ZrO₂/β″-Al₂O₃ and the toughening mechanism of ZrO₂ of c-ZrO₂/β″-Al₂O₃ composites and of t-ZrO₂/β″-Al₂O₃ composites.Direct particle coalescence was identified as magor growth mechanism but ostwald ripering was also observed to contribute. The coalescence of ZrO₂ particles progressed via encounter and spheroidization processes. The increase of fracture toughness leads to an increased strength of c-ZrO₂/β″-Al₂O₃ and t-ZrO₂/β″-Al₂O₃. Dispersion toughening is the toughening mechanism of c-ZrO₂.
Stress-induced transformation toughening is the predominant toughening mechanism of t-ZrO₂. Dispersion toughening also contributes to the increase of fracture toughness of the t-ZrO/β″-Al₂O₃.