Elucidating the mechanical response and microstructure evolution of the constituent layers in gradient-structured Cu alloys

Abstract

The design of gradient structure (GS) in metallic materials has been reported to obtain superior mechanical properties due to the interaction between the GS layer and the coarse-grained (CG) matrix. In this study, the mechanical response and microstructural evolution of the corresponding constituent layers of GS Cu-4.5Al alloy at different pre-strains were systematically investigated. The tensile results showed that the strain hardening capability of the GS layer was improved due to the constraint of the CG matrix. Meanwhile, an extra strengthening was observed at the interface between the GS layer and the CG matrix, resulting in a higher yield strength of the CG matrix constrained by the GS layer than that of the CG matrix without the GS layer constraints. Moreover, the extra strengthening at the interface of the GS and CG matrix was gradually reduced with increasing pre-strain due to the weakening of the interaction at the interface. Microstructural observations at the interface between the GS layer and the CG matrix revealed that more dislocations and twins were activated during pre-strain in the CG matrix having GS constraints than that of the CG matrix without GS constraints. The present work provides important insights on the interaction between constituent layers, in terms of the mechanical response and microstructure evolution.

Keywords

• Cu-4.5Al alloys
• Gradient structure
• Mechanical response
• Microstructure evolution
• Extra strengthening