Strain-assisted consolidation and performance evaluation of steel-containing copper composite

A high-performance copper matrix composite (CuMC) consisting of high-purity copper reinforced with 4 wt% steel particles containing 1.8 wt% carbon was developed using a deformation-driven metallurgy approach, producing distinct microstructural and mechanical gradients through its thickness. The copper matrix showed a pronounced refinement gradient, with grain size decreasing from about 10 μm in the lower region to below 1 μm near the top surface. A comparable trend was also observed for the steel reinforcements, whose average size declined from 8.7 μm to 1.1 μm. These structural changes are closely associated with the spatial variation in deformation conditions, particularly the strain rate (16–20 s −1 ) and temperature (535–625 °C), as reflected by the Zener–Hollomon relationship. The surface region displayed the greatest hardening effect, reaching nearly 185 HV, and also showed the highest level of internal lattice distortion, as indicated by GOS value of 3.8°, respectively. In contrast, these values gradually dropped toward the interior, where the hardness was around 121 HV and the GOS value was 1.6°. Mechanical evaluation under compression confirmed excellent behavior, with the composite achieving a yield strength of 623 MPa, an ultimate compressive strength of 947 MPa, and a fracture strain of 22.1%, clearly outperforming pure copper as well as conventional theoretical predictions. Although steel was introduced as a reinforcement phase, the material still retained a high electrical conductivity of roughly 90% IACS, representing only a limited reduction of about 7% compared with unreinforced copper.