This program examines the role of grain boundaries in affecting superplasticity. Two aluminum-based alloys are selected for the studies. These alloys are produced by two methods, mechanical alloying and powder metallurgy. The deformation characteristics and grain boundary properties are determined and correlated with the measured superplastic behavior. Transmission electron microscopy is used to examine grain misorientations. Scanning electron microscopy is employed to determine the extent of grain boundary sliding. An improved model of superplastic forming should result. %%% A fundamental understanding of grain boundary properties in fine- grained alloys is needed for future development of enhanced superplasticity in metal alloys. This type of processing can result in low cost, near-net shape forming of structural metal components.
