異なる集合組織を持つCu–Zn系合金におけるヘテロナノ組織の発達過程

抄録

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.