Deformation structures and strengthening mechanisms in an Al-Cu alloy subjected to extensive cold rolling

Abstract

The deformation structures, mechanical properties and strengthening mechanisms of a 2519 aluminum alloy subjected to cold rolling up to a total reduction of 80% (ε ~ 1.61) in the supersaturated solid solution condition were studied. The formation of cell structure and a one hundred-fold increase in lattice dislocation density up to ∼ 2.1 × 1015m−2 after a 40% reduction leads to increase in yield stress (σYS) and ultimate tensile strength (σUTS) from 135 to 453MPa, from 350 to 503MPa, respectively. The formation of fully lamellar structure and further increase in lattice dislocation up to ρd ~ 5 × 1015m−2 take place at an 80% reduction. As a result, σYS and σUTS increase to 560 and 590MPa, respectively. Yield stress at reductions ≥ 40% are significantly higher than that in an AA2519T87 alloy. Subdivision of initial grains by lamellar boundaries due to deformation banding provide high efficiency of dislocation strengthening due to the accumulation of an extremely high density of lattice dislocations in supersaturated solid solution and retention of sufficient elongation-to-failure of 9% and 5% after reductions of 40% and 80%, respectively.