Recrystallisation and bonding behaviour of ultra fine grained copper and Cu–Cr–Zr alloy using ECAP

Abstract

The structure, thermal stability and diffusion bonding behaviour of oxygen free high conductivity copper (OFHC), and Cu–Cr–Zr alloy (CRZ) with ultra fine grains (UFG) produced by severe plastic deformation through equal-channel angular pressing (ECAP) are investigated. Microstructural study reveals a grain refinement from 150 μm to 200 nm sized grains after 8 ECAP passes. Thermal stability of ECAP processed OFHC and CRZ has been investigated. Both OFHC and CRZ show hardness reduction at temperatures above 100 °C. However CRZ exhibits grain size stability up to a temperature of 500 °C. Diffusion bonding studies reveal that bond strengths of ∼54 MPa are developed between ECAP processed CRZ and OFHC at a lower temperature of 500 °C when compared to annealed materials.