Effect of bimodal grain size and gradient structure on heterogeneous deformation induced (HDI) stress and mechanical properties of Cu

Abstract In this study, two different types of heterogeneous structures were prepared by controlling surface mechanical attrition treatment (SMAT) time (5 s, 10 30 60 s). The effect Cu with bimodal grain size structure (BGSS) and gradient (GS) on deformation induced (HDI) stress properties was investigated systematically. By combining morphology microhardness distribution, it found that the grains SMAT-ed s s) partially refined to exhibit BGSS, while (30 sufficiently form GS. load-unload-reload (LUR) tests results showed HDI for SMAT 60s much higher than 10s Cu. Furthermore, microstructure characterizations revealed BGSS GS suppressed strain localization, which resulted in high strength reasonable ductility.