9300217 Mukherjee This research examines fundamental deformation mechanisms of superplasticity in intermetallics with special emphasis on the role of interfaces. Superplasticity is the ability of some crystalline materials to undergo large neck-free tensile strain at elevated temperatures. An important feature of superplasticity is the phenomenon of grain boundary sliding. This research explores the influence of grain and phase interfaces on the superplasticity process. Areas of investigation include the role of cooperative grain boundary migration, measurements of internal friction due to grain boundary sliding with correlations to mechanical testing parameters, and effects of interfacial back stress on the rate parameters in the constitutive equation for superplasticity. %%% This research is aimed at improved understanding of superplastic behavior and addresses the application of this phenomenon to intermetallic alloys. The results are valuable to near-net shape processing of materials and automated manufacturing. ***
