Equal-Channel Angular Pressing (ECAP) and High-Pressure Torsion (HPT)

ECAP and HPT are used to fabricate ultrafine-grained microstructures with grain sizes <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 more homogeneous microhardness after 5 turns (lower).

Materials processed by ECAP and HPT are under evaluation for use in superplastic forming operations.

Creep and Superplasticity Creep and Superplasticity in Materials with Ultrafine Grain in Materials with Ultrafine Grain

SizesSizesTerence G. Langdon, University of Southern California, DMR 0243331

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 55, 203 (2007).

M. Kawasaki and T.G. Langdon, “Properties of Superplasticity in Ultrafine-Grained Materials,” Journal of Materials Science 42, 1782 (2007).

Al-6061: P = 4 GPa, 5 turns

Al-6061: P = 4 GPa, 1 turn

Creep and SuperplasticityCreep and Superplasticityin Materials with Ultrafine Grain Sizesin Materials with Ultrafine Grain SizesTerence G. Langdon, University of Southern California, DMR 0243331

Training

2 graduate students (Megumi Kawasaki and Roberto Figueiredo) and 1 post-doc (Dr. Cheng Xu) are participating in this research.

Collaborations are in place with Kyushu University, Japan, and the University of Southampton, U.K.

Impact

Invited lectures describing the results were presented at international conferences in Canada, Germany, Japan, Poland, Russia, Spain, U.K., U.S.A.

The P.I. co-organized conferences on Ultrafine-Grained Materials in Spain (2003); Charlotte, N.C. (2004); Japan (2005); San Antonio, TX (2006); Ufa, Russia (2007).

The post-doc (Dr. Cheng Xu) and student (Megumi Kawasaki) won awards for best oral presentations at the TMS Annual Meetings in Charlotte, N.C. (2004) and San Antonio, TX (2006).

(From left) Megumi Kawasaki, Prof. Langdon, Dr. Cheng Xu and Roberto Figueiredo at the BNM-2007 International Symposium on Bulk Nanostructured Materials in Ufa, Russia, in August 2007