Superplastic Bulging of Fine‐Grained Zirconia

A tetragonal zirconia containing 2 mol% Y 2 O 3 , with 0.3 mol% CuO addition as a grain‐boundary phase, was superplastically stretched at 1150°C using a hemispherical punch. Mechanical analyses were performed to establish that a biaxial tensile stress/strain state was achieved in the process with a maximal strain of 0.5 in the thinned hemispherical shell. The material was damage tolerant up to a critical strain rate, approximately 10 −3 s −1 .