Selective doping of 3Y-TZP with CuO for near net shape forming

A study of the superplastic deformation of 3Y-TZP with varying amounts of liquid CuO grain boundary phase was performed. It was found that the strain rate sensitivity (m0.37) did not vary significantly with small CuO additions, indicating that the fundamental mechanism of superplasticity in 3Y-TZP may not change with small additions of CuO. The dependence of strain rate on CuO concentration was observed to be exponential up to a CuO concentration of approximately 0.3 mol%. This relationship between strain rate and CuO concentration was then used in the prediction of the deformed shapes of selectively CuO-doped samples. By intentionally varying the concentration of CuO throughout a 3Y-TZP sample, it was possible to tailor the amount of superplastic deformation occurring at different locations within the sample and to produce well defined, complex geometries under simple stress fields. The deformation of selectively doped 3Y-TZP samples could be reasonably predicted through an upper bounds analysis of the deformation of cylinders that included corrections in strain rate for the CuO concentration profile across the sample. By differing the heat treatment of these selectively doped samples before deformation, the CuO concentration profile, and thus the final profile of the pellets, could be altered.