Evolution of Microstructure and Grain Growth in Zr02-Y203 Alloys

Abstract

The microstructure evolution and grain growth during high-temperature heat treatment in ZrO2-4 and 8mol%Y2O3 alloys were examined. ZrO2-8mol%Y2O3 alloy was of single cubic phase (c-ZrO2), while ZrO2-8tmol%Y2O3 alloy consisted of mixed grains of c-Zr02 and tetragonal phase (t-Zr02) with the equilibrium yttria contents after a certain period of heating. This structure was different from the microstructure containing precipitates in grain interior, and was referred to be the dual-phase structure. The grain growth of dual-phase structure was much slower than that of single c-ZrO2. The grain growth kinetics of dual-phase structure under the equilibrium partitioning of yttria between c-Zr02 and i-ZrO2 grains could be described by the rate equation which was derived by assuming the growth of individual grains limited by grain-boundary diffusion of yttrium ions. © 1989, The Iron and Steel Institute of Japan. All rights reserved.