Cavity nucleation and growth in superplasticity

Most superplastic materials fail by the nucleation, growth and interlinkage of cavities. Professor Langdon was amongst the first to recognize the significance of concurrent cavitation in superplasticity. This report examines the relaxation of stress concentrations caused by grain boundary sliding, and the nucleation of cavities at triple points, which is relevant for many superplastic ceramics as well as some Mg alloys. It is shown that cavity growth is dominated by plastic deformation. Data for superplastic zirconia are utilized for purposes of illustration. Experimental conditions to limit concurrent cavitation are also identified.