Direct Bonding of Aluminum–Copper Metals through High-Pressure Torsion Processing

High-pressure torsion (HPT) is used to investigate the formation of a new metal system by the direct bonding of separate disks of Al and Cu by processing at room temperature under a compressive pressure of 6.0 GPa and with increasing numbers of HPT turns up to 60. A detailed examination of the microstructure and a phase analysis reveal the presence of three intermetallic compounds, Al₂Cu, AlCu, and Al₄Cu₉, in the nanostructured Al matrix with a grain size of ≈30 nm. Processing by HPT leads to the formation of a metal–matrix nanocomposite with extreme hardness near the edge of the Al–Cu disks after 60 HPT turns. Experiments show that the estimated wear rates exhibit an improvement in wear resistance while maintaining low wear rates for high applied loads up to ≈40–50 N under dry sliding conditions. The results confirm that there is a significant potential for using HPT processing in the joining and bonding of dissimilar metals at room temperature and in the expeditious fabrication of a wide range of new metal systems having enhanced mechanical and functional properties.