Regularities of Microstructure Evolution in a Cu-Cr-Zr Alloy during Severe Plastic Deformation.

The effect of severe plastic deformation by the conforming process of equal channel angular extrusion (ECAE-Conform) followed by cold rolling on the microstructures developed in a Cu-0.1Cr-0.1Zr alloy was investigated. Following the ECAE-Conform of 1 to 8 passes (corresponding strains were 0.8 to 6.4) cold rolling to a total strain of 4 was accompanied by substantial grain refinement and strengthening. An average grain size tended to approach 160 nm with an increase in the rolling reduction. An increase in the ECAE-Conform strain promoted the grain refinement during subsequent cold rolling. The fraction of the ultrafine grains with a size of 160 nm after cold rolling to a strain of 4 increased from 0.12 to 0.52 as the number of ECAE-Conform passes increased from 1 to 8. Correspondingly, the yield strength increased above 550 MPa. The strengthening could be expressed by a Hall-Petch type relationship with a grain size strengthening factor of 0.11 MPa m 0.5 .