Tailoring the microstructure, mechanical properties, and electrical conductivity of Cu–0.7Mg alloy via Ca addition, heat treatment, and severe plastic deformation

The effects of 0.1 wt.% Ca addition, heat treatment, and SPD processing using the MaxStrain module of the Gleeble thermomechanical simulator on the microstructure, mechanical properties, and electrical conductivity of Cu–0.7Mg (wt.%) alloy were investigated in this work. The binary alloy exhibited a single-phase microstructure, whereas the ternary alloy featured uniform dispersion of Cu₅Ca intermetallic particles inside the grains as well as on grain boundaries. These particles resulted in an average hardness that was 33% higher than that of the binary alloy, as well as 13% higher yield strength and 13% higher ultimate tensile strength. The heat treatment process not only enhanced the yield strength and ultimate tensile strength of the samples, but also resulted in the partial spheroidization of Cu₅Ca particles within the microstructure of the ternary alloy, resulting in its improved ductility. Following MaxStrain processing, ternary samples exhibited a smaller grain size and a higher fraction of high-angle grain boundaries than binary samples, which was attributed to the vital role of Cu₅Ca intermetallic particles in hindering the dislocation motion during deformation. MaxStrain-processed samples exhibited marginally lower electrical conductivities than their initial counterparts; yet, all MaxStrain-processed samples satisfied the electrical conductivity threshold for classification as HSHC Cu alloys.