Al-5Cu alloy processed by equal-channel angular pressing

Abstract

An ECAP (equal channel angular pressing) processed UFG Al-5Cu alloy was characterized by electron backscatter diffraction (EBSD). It is revealed that a bimodal grain structure, i.e. ultrafine grains accompanied by micron-sized grains was developed after 4 passes. A high strength (~501 MPa) and a relatively large elongation to failure (~28%) with ~5% uniform elongation were achieved simultaneously after four passes of ECAP. The high strength is due to a combination of strengthening by solute, high dislocation density and ultrafine grains. The enhancement of uniform elongation is primarily due to the enhanced work hardening resulted from the solute Cu content and the bimodal grain structure. The large post-uniform elongation is attributed to the high strain rate sensitivity of the UFG Al-5Cu alloy. More importantly, the present work revealed that during ECAP high solid solution content of Cu and coarse secondary phase particles can introduce inhomogeneous deformation resulting in a desirable bimodal grain structure, which can be utilized as a strategy to gain both high strength and relatively good ductility.