9602919 Langdon This award supports a three-year collaborative research project between Professor Terence G. Langdon of the University of Southern California in Los Angeles and Professor Minoru Nemoto of Kyushu University in Japan. This research investigates processing parameters and microstructural characteristics that are associated with ultrafine grained materials, including the influence of microstructure and concurrent microstructural evolution on the mechanical properties of materials at elevated temperatures. The research employs a new processing method "equal channel angular pressing (ECA)" to create nanocrystalline metal and magnesium alloys. Past experiments have established that metallic alloys with ultrafine grain sizes in the nanometer range have the potential for high ductilities and superplastic-like flow at relatively low temperatures. ECA provides a capability for producing intense plastic straining that can refine the metal alloy grain size into the nanometer range. Aluminum and aluminum-based alloys and copper and magnesium alloys are selected for the study because this selection allows an evaluation of the role of stacking fault energy and its effects on dislocation networks and grain boundary structure. This collaboration will facilitate the extensive expertise in mechanical testing of the Americans with the considerable experience in microstructural analysis of the Japanese. The research could lead to a new processing technique for deformation processing of nanocrystalline materials and could impact future metal alloy processing in the metal forming industries. Through the exchange of ideas and technology, this project will broaden our base of basic knowledge and promote international understanding and cooperation. ***
