Improving strength and corrosion resistance of the Cu-0.2Be-0.8Ni-0.1Al alloy via a dual-layer microstructure

Simultaneous enhancement of strength and corrosion resistance is imperative to extend the application and service life of low-beryllium copper alloys. Here, a distinctive dual-layer microstructure, including a 240 μm-thick gradient fine-grain surface layer with sparse precipitates and a deformed coarse-grain matrix containing dense precipitates, is produced in the Cu‑0.2Be‑0.8Ni‑0.1Al alloy via rolling to matrix and ultrasonic modification to surface layer followed by aging. This architecture delivers high tensile strength (868.2 MPa) and low corrosion current density (2.1 μA/cm 2 ), significantly outperforming those of the conventionally aged alloy (421.6 MPa and 5.1 μA/cm 2 ) and the rolled-aged alloy (752.4 MPa and 19.7 μA/cm 2 ). The enhanced strength results from synergistic effects of grain boundary, deformation, precipitation and hetero-deformation-induced strengthening. The improved corrosion resistance arises from the ultrafine-grained surface layer with spare precipitates, which can form dense and stable passive film and suppress the micro-galvanic corrosion. This study provides a viable microstructural design strategy for developing high-performance low-beryllium copper alloys with high strength and good corrosion resistance.