Effect of Equal Channel Angular Pressing on Microstructure and Mechanical Properties of a Cu-Mg Alloy

Muzhi Ma,Hongyun Jiang,Ziqi Xia,Xi Zhang,Zhou Li,Hanyan Huang,Zhu Xiao

doi:10.3390/cryst10060426

Abstract

A Cu-0.43Mg (wt.%) alloy was processed by equal channel angular pressing (ECAP) up to eight passes via a processing route (Bc). The hardness distribution on the longitudinal and transverse sections was collected and the microstructure in the central and bottom regions on the longitudinal section was examined. The result showed that the hardness was improved significantly at the initial stage of the ECAP process, and the lower hardness region appeared at the area nearby the bottom surface. With the number of ECAP passes, the hardness gently increased and finally became saturated. The inhomogeneity of the hardness distribution along the normal direction gradually weakened and finally disappeared. The shear microstructure in the central region was different from that in the bottom region after one ECAP pass, and they became similar to each other after two ECAP passes, except the rotation angle of the elongated grains. With the further increasing ECAP passes, there was no obvious microstructure difference between the central and bottom regions. The inhomogeneities of the hardness and the microstructure along the normal direction in the alloy after one ECAP passes should be attributed to the non-zero outer arc of curvature of the ECAP die and the friction between the bottom surface of the billets and the ECAP die walls. The yield strength of the alloy increased from 124 MPa before the ECAP process to 555 MPa after eight ECAP passes. The improvement of yield strengths of the ECAPed Cu-Mg alloy should be mainly attributed to the dislocation strengthening and the grain boundary strengthening.

Highlights

Copper alloys play a vital role in mechanical manufacturing, railway transportation, electrical and electronic industries [1,2,3,4]
Many researchers have attempted to improve the comprehensive properties of the Cu-Mg alloy via the microalloying method [10,11,12,13], but the solute atoms introduced by Crystals 2020, 10, 426; doi:10.3390/cryst10060426
Walls and turn the walls At nothe longer impose of bewith attributed to thedie formation of aincorner gapdie corner gap, the billets shear no strain on the billets

Summary

Introduction

Copper alloys play a vital role in mechanical manufacturing, railway transportation, electrical and electronic industries [1,2,3,4]. Cu-Mg alloys have been widely applied as the contact wire and other conductor materials in the high-speed rail industry due to their good combination of high strength and high electrical conductivity [5,6,7,8]. Crystals 2020, 10, 426 the microalloying method could significantly and inevitably decrease the electrical conductivity of the Cu-Mg alloy [14]. The severe plastic deformation (SPD) technique can effectively improve the strength of copper alloy without decreasing its high electrical conductivity [15]. The most attractive one is the equal channel angular pressing (ECAP) technique. The ECAP process involves that the metallic material is deformed by pressing through an equal cross-sectional channel with the right or obtuse angle [16].

Methods

Results

Discussion

Conclusion