GRAIN-GROWTH AND PHASE-SEPARATION OF ZRO2-Y2O3 CERAMICS ANNEALED AT HIGH-TEMPERATURE

The behavior of grain growth and phase separation of sintered ZrO2-2-8 mol.% Y2O3 ceramics annealed at high temperatures were investigated by means of SEM, EPMA, XRD and quantitative metallography. The results show that the grain size increases with increasing Y2O3 content and annealing time. The grain growth is very slow in the single tetragonal phase region and very fast in the single cubic phase region. However, in the c + t two-phase region, the cubic grains grow more slowly, but the tetragonal grains more quickly than in the single cubic or tetragonal phase regions. With the increase of annealing time in the c + t two-phase region, the Y2O3 content in the tetragonal phase decreases, but remains almost unchanged in cubic phase.