DEFORMATION AND GRAIN-GROWTH OF LOW-TEMPERATURE-SINTERED HIGH-PURITY ALUMINA

Through close control over green‐state powder processing, pure alumina ceramics of 0.5‐μm grain size were obtained by sintering at 1250°C. The static grain growth of this material was modest at temperatures below 1300°C. However, dynamic grain growth occurred rapidly during superplastic deformation. Therefore, although the ultrafine‐grained alumina exhibited rather low initial flow stress at relatively low deformation temperatures, dynamic grain‐growth‐induced strain hardening gave rise to high flow stress causing cavitation and cracking. As a result, superplastic deformation could not be achieved for the ultrafine‐grained pure alumina. Copyright © 1990, Wiley Blackwell. All rights reserved