Superplastic joining of 3Y-TZP

The microscopic processes and mechanisms for the superplastic joining of 3Y-TZP (3 mol% yttria partially stabilized tetragonal zirconia polycrystals) were examined. The cooperative grain-boundary sliding associated with superplastic deformation and flow plays an essential role in the joining at the interface between 3Y-TZP blocks. The mechanical strength of the joined interface was determined by three-point flexural loading, where three different types of joined interfaces were studied; the interfaces between (1) fine-grain-size 3Y-TZPs, (2) coarse-grain-size 3Y-TZPs, and (c) a fine-grain-size and a coarse-grain-size 3Y-TZPs. The strengths of these interfaces were examined by changing the compressive stresses applied to the interfaces during joining. It was concluded that the mutual migrations of grains across the interface through cooperative grain-boundary sliding (CGBS) dominates the strength evolution at the interface along with thermally activated diffusion processes.