Towards high strength and ductility of Al–Cu-Mg alloy via cyclic and monotonic pre-straining followed by ageing

Abstract

This article presents an investigation of the ageing response of modern high-strength aluminium alloy 2519 (Al–5.64Cu-0.33Mn-0.23Mg-0.01Si (wt%)) after cyclic strengthening (CS). The impact of the pre-straining value on the mechanical properties, microstructure and phase composition was elucidated via hardness and tensile testing, analytical transmission and orientation imaging electron microscopy. The results show that cyclic hardening has a significant impact on the ageing behaviour of the alloy. Applying cyclic pre-straining in conjunction with monotonic enhances strength and ductility at once. This novel high-performance treatment results in superior strength-ductility combination. The improved mechanical properties are attributed to the observed changes in microstructure. The introduction of vacancies and dislocations, by repetitive and elastic straining before artificial ageing, leads to great homogeneous structure and an increase in the number density and volume fraction of the main strengthening phases (θ′ and Ω) and clusters/zones. Therefore, this work should suggest a strategy for developing a novel treatment of aluminium alloys with excellent mechanical properties.