A novel method for achieving gradient microstructure in a Cu-Al alloy: Surface Spinning Strengthening (3S)

Abstract

A new designed surface strengthening method, surface spinning strengthening (3S), was applied to achieve gradient microstructure in the surface layer of a Cu-11 at.%Al alloy. According to the level of grain refinement, the gradient microstructure can be divided into four zones, including nanoscale grain zone, ultra-fine grain zone, fine grain zone and coarse grain zone from the surface to the matrix. Meanwhile, a plenty of grain boundaries and twin boundaries were introduced to inhibit the dislocation motion in the surface layer during the plastic deformation process. Consequently, the hardened layer with a microhardness gradient and high residual compressive stress was produced on the samples, and the yield strength of the Cu-11 at.%Al alloy was effectively improved after 3S processing due to the strengthening effect caused by the gradient microstructure.