MIGRATION OF INTERGRANULAR BOUNDARIES IN CUBIC ZIRCONIA YTTRIA INDUCED BY MAGNESIA ADDITION

When partially sintered cubic ZrO2–10 mol% Y2O3 specimens are heat‐treated at 1500°C with 5MgO·95(ZrO2–10 mol% Y2O3) powder mixture in the pores, the intergranular boundaries, which may be either grain boundaries or thin glass films, migrate, leaving behind them a new solid solution slightly enriched with MgO but depleted of Y2O3. The boundary curvatures generally increase during the migration and the average migration distance initially increases linearly with the heat treatment time. The observed boundary migration behavior is similar to that observed previously in a number of metallic systems, and its driving force is believed to arise from the coherency strain in the thin solute diffusion zone ahead of the moving boundaries. Copyright © 1990, Wiley Blackwell. All rights reserved