Formation of Deformation Twins and Related Shear Bands in a Copper Single Crystal Deformed by Equal-Channel Angular Pressing for One Pass at Room Temperature

Abstract

Deformation twinning, which is extremely difficult to produce in face-centered cubic (FCC) crystals with medium to high stacking fault energy (SFE), was observed in pure copper single crystals with an appropriate crystallographic orientation subjected to equal-channel angular pressing (ECAP) for one pass at room temperature. Dense shear bands were also observed, delineated by large-angle grain boundaries, and with close to a twinning relation with the matrix, suggesting the role of deformation twinning at their nucleation sites. The activation of deformation twinning is rationalized by a favorable crystallographic orientation and predominant dislocation density in a primary slip system.