Development of Heterogeneous Nano-Structures in a Cu-Zn Alloy with Different Initial Textures

The effect of initial texture on the formation of deformation twins and its impact on the final heterogeneous nano-structure (HN-structure) and mechanical properties of a Cu-Zn-Sn alloy with an extremely low stacking fault energy during cold rolling were systematically investigated. Specimens with an accumulation of 〈111〉 along the normal direction (ND) were prepared and cold-rolled up to 90% reduction in thickness. Two different rolling directions (RD) were applied: one with a high accumulation of 〈211〉 along RD (211 specimen) and another with a 〈110〉 orientation (110 specimen). The 211 specimens exhibited higher volume fractions of twinned grains in the early stages of rolling (∼50% reduction) than the 110 specimens. In the later stage of rolling (60∼90% reduction), the HN-structure consisting of deformation twin domains, lamellar grains and shear bands was well developed in both specimens. However, the 〈211〉 specimen exhibited a higher fraction of twin domains with 111〈211〉 orientation, whereas the 〈110〉 specimen contained more 111〈110〉 twin domains. The highest strength-ductility balance was achieved at an 80% reduction, with the 211 specimen exhibiting a higher strength-ductility balance. The higher strength of the 211 specimen is attributed to the higher fraction of 111〈211〉 twin domains, which offer greater resistance to plastic deformation compared to 111〈110〉 twin domains.