Microstructural developments during sintering in 2 and 3mol% Y2O3-stabilized tetragonal zirconia polycrystals (2Y- and 3Y-TZPs) and 8mol%Y2O3-stabilized cubic zirconia (8Y-CSZ) were systematically investigated for sintering temperatures ranging from 1100 to 1500C. Above 1200C, grain growth in 8Y-CSZ was much faster than that in 2Y- and 3Y-TZPs. In the grain-boundary faces in these specimens, amorphous layers did not exist; however, Y3+ ions segregated at the grain boundaries over a width of  ≈10nm. The amount of segregated Y3+ ions in 8Y-CSZ was significantly less than in 2Y- and 3Y-TZPs. This indicated that an increase in segregated Y3+ ions retards grain growth. Therefore, grain growth behavior during sintering could be reasonably explained by the solute-drag mechanism of Y3+ ions segregating along the grain boundary. The segregation of Y3+ ions, which directly affects grain growth, was closely related to the driving force for grain-boundary segregation-induced phase transformation.

Grain-Boundary Structure and Microstructure Development Mechanism in 2–8mol% Yttria-Stabilized Zirconia Polycrystals. K.Matsui, H.Yoshida, Y.Ikuhara: Acta Materialia, 2008, 56[6], 1315-25