Dislocation behavior and strengthening mechanisms of Cu–Te alloy drawn at room and cryogenic temperatures

Abstract

In the work, the cryogenic and room temperature drawing behaviors of Cu–Te alloy with a wide range of accumulative drawing true strain up to 1.1 are systematically investigated. For the first time, the storage of geometrically necessary dislocations (GND) and statically stored dislocations (SSD), occurrence of deformation twinning, as well as their respective roles in strain hardening in the drawn Cu–Te alloy at cryogenic and room temperature have been studied. The results show that the liquid nitrogen temperature drawn (LNT-D) Cu–Te alloy presents higher yield strength (YS), ultimate tensile strength than the room temperature drawn (RT-D) Cu–Te alloy. Microstructural investigation reveals that cryogenic wire drawing of Cu–Te alloy promotes the formation of simultaneous twinning and shear bands, accompanied by the fragmentation of Cu2Te phase. The LNT-D Cu–Te alloy exhibits planar slip characteristics, while RT-D Cu–Te alloy presents wave slip characteristics. Compared with RT-D Cu–Te alloy, the higher YS of LNT-D Cu–Te alloy can be mainly attributed to dislocation strengthening and twinning strengthening, which account for 76.25–80.45% and 4.79–4.91% of the total YS respectively. During room temperature drawing, both GND and SSD play an important role in the hardening of Cu–Te alloy. During cryogenic temperature drawing, work hardening is predominantly through rapid multiplication of SSDs.

Keywords

• Cu–Te alloy
• Deformation twin
• Geometrically necessary dislocations
• Statistically stored dislocations
• Cryogenic drawing