Gradient Nano-Grained Cu and Cu-Zn Alloys Processed by Surface Mechanical Attrition Treatment

Abstract

Cu and Cu-30wt.%Zn alloys with stacking fault energies (SFEs) of 78 mJ/m2 and 14 mJ/m2 were processed by surface mechanical attrition treatment (SMAT) at room temperature and liquid nitrogen (LN) temperature, respectively. The effect of SFE and deformation temperature on tensile properties of these samples was investigated. The tensile testing results indicated that the yield strength and uniform elongation of these samples enhanced simultaneously with decreasing SFE. Meanwhile, the LN-SMAT processed samples exhibited remarkably higher strength and slightly lower ductility compared to those processed at room temperature. The SFE affected the deformation mechanisms of metals greatly. X-ray diffraction (XRD) measurements indicated that the twin density increased while the average grain size decreased with SFE decreasing, and twinning became the dominant deformation mechanism. The relationship between microstructure and mechanical property is also discussed.