Manufacturing of Conductive Wear-Resistant Nanoreinforced Cu-Ti Alloys Using Partially Oxidized Electrolytic Copper Powder

摘要

Reactive powder composites Cu-(0–15%)TiH containing up to 5% native Cu O were manufactured by high energy ball milling and then hot-pressed to produce bulk nanostructured copper–matrix alloys reinforced by Cu Ti O inclusions. Two high-energy ball-milling (HEBM) protocols were employed for the fabrication of Cu-Ti alloys: single-stage and two-stage ball milling, resulting in an order of magnitude refinement of TiH particles in the reactive mixtures. Single-stage HEBM processing led to the partial retention of Ti in the microstructure of hot-pressed specimens as the α-Ti phase and formation of fine-grained (100–200 nm) copper matrix interspersed with 5–20 nm Cu Ti O precipitates, whereas the two-stage HEBM led to the complete conversion of TiH into the Cu Ti O phase during the hot pressing but produced a coarser copper matrix (1–2 μm) with 0.1–0.2 μm wide polycrystalline Cu Ti O layers on the boundaries of Cu grains. The alloy produced using single-stage HEBM was characterized by the highest strength (up to 950 MPa) and electrical conductivity (2.6 × 10 Sm/m) as well as the lowest specific wear rate (1.1 × 10 mm /N/m). The tribological performance of the alloy was enhanced by the formation of Cu Ti O microfibers in the wear debris, which reduced the friction coefficient against the Al O counter-body. The potential applications of the developed alloys are briefly discussed.