The Effects of Alloying and Pressing Routes in Equal Channel Angular Pressing of Cu-Fe-Cr and Cu-Fe-Cr-Ag Composites

Abstract

Equal channel angular pressing (ECAP) was carried out on Cu-Fe-Cr and Cu-Fe-Cr-Ag composites at room temperature. ECAPed Cu-Fe-Cr and Cu-Fe-Cr-Ag exhibited ultrafine-grained microstructures with the shape and distribution of Fe-Cr phase were dependent on the processing routes. In route A, the initial dendrites of Fe-Cr phase were elongated along the shear direction and developed into filaments, whereas in route Bc the initial dendrites became finer by fragmentation with no pronounced change of the shape. The hardness of ECAPed Cu-Fe-Cr-Ag is greater than that of ECAPed Cu-Fe-Cr. The higher hardness in Cu-Fe-Cr-Ag is ascribed to the more effective matrix strengthening due to the dislocation storage and the precipitation hardening. The hardness of ECAPed Cu-Fe-Cr was lower than that of the drawn Cu-Fe-Cr at the same deformation strain because of the less effective refinement and elongation of the two-phase filamentary microstructure. The addition of silver was found to increase the hardness of the ECAPed composite above the strength level of heavily drawn Cu-Fe-Cr, rendering the processing method of applying alloying and ECAP to Cu-Fe-Cr composite an attractive approach to producing bulky high strength Cu base composites.