Variation of Cu Distribution in Surface Oxide Layer of Ti-Cu Alloy with Heat Treatments

Surgical treatment of severe bone fractures is possible using Ti alloy-based artificial bone. However, infections caused by bacterial proliferation at the replacement material remain a critical issue. This study aimed to add antibacterial properties to Ti by adding Cu, which was recognized for its antibacterial effects. Ti-(5, 8, 10 at%)Cu alloys were fabricated, and heat treatments were performed at temperatures ranging from 300 to 1000°C in the Ar and Ar-2% O₂ gas atmosphere. The effect of heating temperature and atmosphere on the distribution of Cu at the sample’s surface was investigated. Figure 1 shows the depth profile of Cu concentration of as-polished and heat-treated Ti-10 at%Cu alloys evaluated using XPS. The Cu concentrations at the surface of the as-polished sample and the heat-treated samples at temperatures above 700°C were lower than the average Cu concentration, 10 at%. The enrichment of Cu at the surface of the oxide layer formed on the sample’s surface is achievable through the heat treatments in an Ar or Ar-2% O₂ atmosphere at 500°C. The appropriate heat treatments avoid the formation of the Cu-depleted layer on the surface of Ti-Cu alloys, expecting to maintain the antimicrobial properties of the alloy.