Orientation Design for Enhancing Deformation Twinning in Cu Single Crystal Subjected to Equal Channel Angular Pressing

Abstract

Slip and twinning are two major mechanisms in plastic deformation of crystalline materials; however, twinning is extremely difficult to occur in face‐centered‐cubic crystals under conventional conditions. The authors show that twinning becomes an active deformation mode in copper single crystal when subjected to equal channel angular pressing at room temperature. In particular, the observations revealed that deformation twinning became more active in the copper single crystal having a proper crystallographic orientation.

Deformation Mechanisms of Single Crystals and Bicrystals Subjected to Equal-Channel Angular Pressing - Review

“…The corresponding SAD pattern indicates that the misorientation among those substructures is small. However, in this scale, there is no any deformation twin in these microbands or cell-block substructures, which is different from the previous observations in Cu single crystals [23]. In order to further reveal the local microstructure information, we observed the Al single crystal by high-resolution TEM.…”

“…7(c) and (d), many deformation twins distribute desultorily and discontinuously in this area, as proved by the corresponding SAD pattern. Extensive observations by TEM revealed that the deformation twins in the present crystal can be categorized into three types according to their locations and morphologies and one can find more details in ref [23]. These experimental results demonstrate that Cu single crystal can deform by twinning at a very low strain rate and at RT during ECAP when a proper crystallographic orientation was specially selected with respect to the ECAP die.…”

Origin of deformation twinning from grain boundary in copper

“…The crystallographic orientation of the Cu single crystal was specially designed to make one of twinning systems, such as ͑111͓͒112͔, just on the macroscopic shear deformation plane of ECAP, which has been described in more detail previously. 26 Some of deformation twins nucleated in the very fine ribbon structures in the region of shear bands, and most of them are in a scale of tens of nanometers except for few of them with a length larger than 100 nm, as reported in more detail elsewhere. 26 After ECAP, thin foils for transmission electron microscope ͑TEM͒ were prepared by twin-jet polishing method.…”

Investigation of microstructure and mechanical properties of Cu-Ni alloy processed by equal channel angular pressing

“…Grain refinement by deformation-twin formation is witnessed in materials with moderate or low stacking fault energy. 38 Han et al 39 showed grain refinement by twinning in single crystal copper by ECAP process at room temperature. Grain refinement by twinning is possible by properly orienting the crystallographic plane with respect to the ECAP die plane.…”