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Pure Al: 1 turn. Pure Al: 5 turns. Creep and Superplasticity in Materials with Ultrafine Grain Sizes Terence G. Langdon, University of Southern California NSF Award MET DMR-0243331. Equal-Channel Angular Pressing (ECAP) and High-Pressure Torsion (HPT)
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Pure Al: 1 turn Pure Al: 5 turns Creep and Superplasticity in Materials with Ultrafine Grain SizesTerence G. Langdon, University of Southern CaliforniaNSF Award MET DMR-0243331 Equal-Channel Angular Pressing (ECAP) and High-Pressure Torsion (HPT) • ECAP and HPT are used to process ultrafine-grained microstructures. • Grain sizes are generally in the range 100-1000 nm. • Hardness measurements demonstrate the development of homogeneity after processing: illustrations (right) show an inhomogeneous microstructure after 1 turn of HPT (upper) and a homogeneous microhardness distribution after 5 turns (lower). • Materials processed by ECAP and HPT are excellent candidate materials for use in superplastic forming operations. C. Xu, M. Furukawa, Z. Horita and T.G. Langdon, “Influence of ECAP on Precipitate Distributions in a Spray-Cast Aluminum Alloy,” Acta Materialia 53, 749-758 (2005). M. Kawasaki, C. Xu and T.G. Langdon, “An Investigation of Cavity Growth in a Superplastic Aluminum Alloy Processed by ECAP,” Acta Materialia 53, 5353 (2005). C.Xu, Z. Horita and T.G. Langdon, “The Evolution of Homogeneity in Processing by High Pressure Torsion,” Acta Materialia (2006) in press.
Creep and Superplasticityin Materials with Ultrafine Grain SizesTerence G. Langdon, University of Southern CaliforniaNSF Award MET DMR-0243331 Training • 3 graduate students and 1 post-doc are participating in this research. • Collaborations are in place with Kyushu University, Japan, and the University of Southampton, U.K. Dr. Cheng Xu and Prof. Langdon prepare ultrafine-grained materials using Equal-Channel Angular Pressing at the University of Southern California Impact • Invited lectures describing the results were presented at international conferences in the Czech Republic, Japan, Poland, Russia, Spain, Ukraine, U.K., U.S.A. • The P.I. is co-organizer of conferences on Ultrafine-Grained Materials in Spain (2003); Charlotte, N.C. (2004); Japan (2005); San Antonio, TX (2006); Ufa, Russia (2007). • The post-doc and student won awards for best oral presentations at the TMS Annual Meetings in Charlotte, N.C. (2004) and San Antonio, TX (2006). Graduate student Megumi Kawasaki with the High-Pressure Torsion facility