Effect of VN and TiB₂-TiC_x Reinforcement on Wear Behavior of Al 7075-Based Composites

Al 7075 alloy, 15 wt.% VN/7075 composites, and 20 wt.% TiB₂-TiC_x/7075 composites were prepared by ball milling with subsequent hot-pressing sintering. The microstructure, hardness, and wear properties at room temperature to 200 °C of Al 7075-based composites with different reinforcement phases were discussed. The grain uniformity degree values of 15 wt.% VN/7075 composites and 20 wt.% TiB₂-TiC_x/7075 composites were 0.25 and 0.13, respectively. The reinforcement phase was uniformly distributed in 15 wt.% VN/7075 composites and 20 wt.% TiB₂-TiC_x/7075 composites, almost no agglomeration occurred. The order of hardness was 20 wt.% TiB₂-TiC_x/7075 composites (270.2 HV) > 15 wt.% VN/7075 composites (119.5 HV) > Al 7075 (81.8 HV). At the same temperature, the friction coefficient of 15 wt.% VN/7075 composites was the lowest, while the volume wear rate of 20 wt.% TiB₂-TiC_x/7075 composites was the lowest. With the increase of temperature, the wear mechanism of Al 7075 changed from spalling wear to oxidation wear and adhesion wear. However, the wear mechanisms of 15 wt.% VN/7075 and 20 wt.% TiB₂-TiC_x/7075 composites changed from abrasive wear at room temperature to wear mechanism (oxidation wear, abrasive wear, and adhesive wear) at medium and low temperature. Comprehensive wear test results indicated that 20 wt.% TiB₂-TiC_x/7075 composites had excellent tribological properties at medium and low temperature.