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Amorphous grain boundary phases in 3-mol%-yttriastabilized zirconia ceramics (3Y-TZP) were studied to determine the influence of intergranular amorphous silicate phases on tensile superplasticity at temperatures of 1300 -1500°C. Controlled additions (1 wt%) of compositionally distinct barium silicate and borosilicate phases were used. The initial grain sizes of the pure, barium silicate added, and borosilicate-added samples were 0.45, 0.55, and 0.55 m, respectively. Systems with added barium silicate and borosilicate glass both exhibited a 60% reduction in flow stress as compared with pure 3Y-TZP, with the lower-viscosity barium silicate system exhibiting a slightly greater reduction in flow stress. The higherviscosity borosilicate glass/3Y-TZP materials exhibited the greatest elongation to failure, while the barium silicate/3Y-TZP materials had the least elongation. Yttrium was found to segregate to grain boundaries in the pure and borosilicatecontaining samples, and both yttrium and barium were found to segregate to grain boundaries in the barium silicate containing samples. No silicon was observed along two-grain boundaries in any of the samples, even those containing pockets of glass. The difference in deformation behavior may be due to a combination of viscosity of the glass addition, grain boundary segregation, and grain boundary bond character.

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