Microstructure and Properties of Oxidation-Induced Layered Composite Structures in Cu-Cr-Zr Alloys

In this study, an “oxide layer” was formed on the surface of Cu-0.97Cr-0.11Zr alloy sheets by introducing oxygen via a non-vacuum solid solution treatment, followed by vacuum solid solution and aging treatments to obtain a layered composite microstructure. The macro- and microstructures were characterized using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Furthermore, the properties of the alloy were evaluated through electrical conductivity and hardness measurements. The results indicate that during the non-vacuum solid solution process, oxygen atoms diffused into the copper alloy matrix and underwent an in situ oxidation reaction with the solute Cr. As the temperature increased from 800 °C to 900 °C, the thickness of the oxide layer grew from 23.2 μm to 77.8 μm. The formation of Cr2O3 nanophases within the oxide layer increased the alloy hardness from 87.3 HV to 101.8 HV and the electrical conductivity from 68.75% IACS to 78.85% IACS. Following subsequent vacuum solid solution and aging treatments, both hardness and electrical conductivity were significantly enhanced, reaching an edge hardness of 114.6 HV, a core hardness of 125.1 HV, and a conductivity of 80.32% IACS. Through this method, a layered composite structure of the Cu-0.97Cr-0.11Zr alloy, characterized by a highly conductive surface and a high-hardness core, can be successfully obtained.