Ductile fracture in copper single crystals

Abstract

Metallographic and x-ray studies in the vicinity of the necks of fractured copper single crystals oriented for multiple slip have shown that initial necking takes place by general deformation followed by localized shearing after a well-developed neck has formed. Lattice rotation was observed to occur in the necked region during general deformation; void growth and quadrangular cavity formation, during localized shear process. In crystals of [112] and [001] orientation, and in twinned crystals of [111] orientation, a symmetrical positioning of slip systems about the stress axis permits the crystals to neck and to undergo large reductions of area, approaching rupture. In crystals of [111] orientation, a particular primary-cross slip combination which is non-symmetrically disposed about the stress axis is most preferred at the inception of localized shear. For this reason, such crystals fractured by shear in a narrow zone parallel to [100].