Microstructural Evolution and Dry Sliding Wear Behavior of a Cu-Cr-Zr Alloy Processed by Cyclic Hot Forging and Short-Time Aging

To elucidate the effect of cyclic hot forging and short-time aging (HFSTA) on the wear resistance of a Cu-Cr-Zr alloy, samples in the as-received state (solution-treated at 1000 °C) and after 4 passes and 6 passes of cyclic HFSTA at 450 °C were prepared. The relationships between microstructure and properties were systematically analyzed. The results indicate that the cyclic HFSTA process did not change the main phase structure of the Cu matrix but significantly tailored the grain morphology, local misorientation, grain boundary character, and tribo-chemical behavior of the surface. The 4-passes sample possessed relatively high hardness, electrical conductivity, and favorable microstructural stability and was able to form a continuous and dense oxide protective film during friction, as demonstrated by the increase in hardness from 86 HV (as-received) to 195 HV, the decrease in average coefficient of friction (COF) from 0.65 to 0.50, and the reduction in wear rate from 13.3 × 10−4 mm3/(N·m) to 0.3 × 10−4 mm3/(N·m). The 6-passes sample exhibited slightly higher hardness, but the increased proportion of low-angle grain boundaries (LAGBs) intensified cracking and spallation on the wear track, causing the wear rate to rebound to approximately 8.2 × 10−4 mm3/(N·m). The study demonstrates that the wear resistance of the Cu-Cr-Zr alloy does not improve monotonically with hardness or grain refinement but is jointly controlled by precipitation strengthening, dislocation/substructure strengthening, surface damage tolerance, and the stability of the tribo-film. For the dry sliding service conditions of Cu-Cr-Zr alloys, 4 passes of cyclic HFSTA at 450 °C represent an optimal processing window that balances mechanical properties, electrical conductivity, and wear resistance, providing guidance for the process optimization of components such as contact wires and welding electrodes.