The Influence of Severe Plastic Deformation and Subsequent Annealing on the Microstructure and Hardness of a Cu–Cr–Zr Alloy

Abstract

A Cu–1.1%Cr–0.04%Zr (wt.%) alloy was processed by severe plastic deformation (SPD) using the equal channel angular pressing (ECAP) technique at room temperature (RT). It was found that when the number of passes increased from one to four, the dislocation density significantly increased by 35% while the crystallite size decreased by 32%. Subsequent rolling at RT did not influence considerably the crystallite size and dislocation density. At the same time, cryorolling at liquid nitrogen temperature yielded a much higher dislocation density. All the samples contained Cr particles with an average size of 1 µm. Both the size and fraction of the Cr particles did not change during the increase in ECAP passes and the application of rolling after ECAP. The hardness of the severely deformed Cu alloy samples can be well correlated to the dislocation density using the Taylor equation. Heat treatment at 430 °C for 30 min in air caused a significant reduction in the dislocation density for all the deformed samples, while the hardness considerably increased. This apparent contradiction can be explained by the solute oxygen hardening, but the annihilation of mobile dislocations during annealing may also contribute to hardening.

Quantitative Study on the Evolution of Microstructure, Strength, and Electrical Conductivity of the Annealed Oxygen‐Free Copper Wires

“…Currently, severe plastic deformation (SPD) technology has been widely used in manufacturing high strength and high conductivity copper and copper alloys. [1][2][3][4] SPD technologies, including equal channel angular pressing (ECAP), high-pressure torsion (HPT), accumulative roll bonding (ARB), and multidirectional forging (MDF), have made outstanding contributions in the field of manufacturing high strength and high conductivity copper. Moreover, the SPDed copper material has exhibited excellent mechanical properties, good electrical conductivity, and bright application prospects.…”

Mechanical Properties of Rolled Copper Foils in Cryogenic and Room‐Temperature Environments

“…These behaviors at cryogenic temperatures are vary greatly different with those at room temperature. [ 9 ] There are many researches on the cryogenic processing of copper foil, such as cryorolling, [ 10 ] equal‐channel angular rolling [ 11 ] and equal‐channel angular pressing + cryorolling, [ 12 ] but few studies on the mechanical properties of rolled copper foil in cryogenic environment.…”

The effect of neutron irradiation on mechanical properties of CuCrZr alloys processed by cryorolling

“…This alloy is designed for lnternational Thermonuclear Experimental Reactor (ITER) and is referred to as CuCrZr-IG, with the chromium content of 0.60-0.90 wt.% and of 0.07-0.15 wt.% zirconium [5]. Increased strength of this alloy can be mainly achieved by precipitation hardening of fine CunZr precipitates, which also leads to a considerable improvement of ductility at elevated temperatures [6][7]. Precipitation of Cr-rich particles during supersaturated solid solution aging at 450-480°C for 2-4 h also results in strengthening.…”

“…In case of life extension of this alloy under severe conditions of radiation, the microstructure modification is required in order to increase the plasticity and thermal stability of the alloy. This can be achieved using the severe plastic deformation (SPD), which is a very effective method of production of bulk ultrafinegrained (UFG) and nanostructured materials with novel characteristics [2,7]. The mechanical properties and microstructure of CuCrZr alloy can be modified by several SPD methods, such as high-pressure torsion (HPT), multi-directional forging (MDF), equal-channel angular pressing (ECAP) and asymmetric rolling (ASR), in some cases also at cryogenic temperatures [7,[10][11][12][13].…”

“…This can be achieved using the severe plastic deformation (SPD), which is a very effective method of production of bulk ultrafinegrained (UFG) and nanostructured materials with novel characteristics [2,7]. The mechanical properties and microstructure of CuCrZr alloy can be modified by several SPD methods, such as high-pressure torsion (HPT), multi-directional forging (MDF), equal-channel angular pressing (ECAP) and asymmetric rolling (ASR), in some cases also at cryogenic temperatures [7,[10][11][12][13]. The increased ductility was observed in Cu-10%Al with UFG structure compared to the conventional coarse-grained alloy [14].…”