Hardness, Electrical Conductivity and Thermal Stability of Externally Oxidized Cu-Al2O3 Composite Processed by SPD

Cu-Al2O3 composites prepared by external oxidation method were further enhanced by severe plastic deformation (SPD) processing, including equal-channel angular pressing (ECAP) and high-pressure torsion (HPT) methods. The HV hardness and electrical conductivity of the samples before and after SPD processing were tested. Results revealed that ECAP samples (with an equivalent strain of about 5.34) showed a relative small increase in hardness, whereas a significant decrease in electrical conductivity. The HPT samples (with an equivalent strain of about 6.94) showed not only a much improved hardness but also a higher electrical conductivity. Thermal stability of the SPD-processed Cu-Al2O3 composites was tested, and the HPT samples maintained good HV hardness together with high electrical conductivity even at 600 degrees C. The combination of external oxidation method and HPT processing resulted in enhanced mechanical properties, good electrical conductivity, acceptable thermal stability, and much simplified oxidation process.