title: Influence of stacking fault energy on defect structures and microhardness of Cu and Cu alloys.
abstract: Nano-structured Cu, Cu-10 wt%Zn and Cu-2 wt%Al with stacking fault energies (SFE) of 78, 35 and 37 mJ/m2, respectively, were preprared through high energy ball milling. X-ray diffraction and Vickers microharness test were used to investigate the microstructure and microhardness of all the samples after ball milling. X-ray diffraction measurements indicate that lower SFEs lead both to decrease in grain size and increase in microstrain, dislocation and twin densities for Cu-10 wt%Zn and Cu-2 wt%Al after 5 h of ball milling. The microhardnesses of Cu-10 wt%Zn and Cu-2 wt%Al reach to nearly the same values of 2.5 GPa after 5 h of ball milling, which is higher than that of Cu of 2.0 GPa. Two factors are considered to contribute to the finer grian size and higher microhardness of Cu-10 wt%Zn and Cu-2 wt%Al: (1) the effect of solid solution strengthening, which result in the interaction of solute atoms with screw dislocations; (2) the introduction of deformation twins during ball milling process by the decreasing of SFE, which results in the grain refinement.
authors.affiliation: Department of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093, China.
authors.forename: Jing-Mei
authors.initials: JM
authors.lastname: Tao
authors.forename: Dai
authors.initials: D
authors.lastname: Li
authors.forename: Cai-Ju
authors.initials: CJ
authors.lastname: Li
authors.forename: Xin-Kun
authors.initials: XK
authors.lastname: Zhu