Effect of fabrication methods on the microstructure and properties of a Cu–Cr–Nb alloy

In comparison to other Cu-based alloys, the high-temperature strength of the studied Cu-4.06Cr-1.25Nb alloy fabricated by the atmospheric melting method was improved significantly. After homogenization at 950 °C for 4 h, hot rolling by 80%, solid solution treatment at 940 °C for 4 h, cold rolling by 50%, and aging at 400 °C for 2 h, the tensile strengths of the Cu-4.06Cr-1.25Nb alloy fabricated by spark plasma sintering (SPS) at 20 °C, 400 °C, 450 °C, and 500 °C were 535 MPa, 256 MPa, 212 MPa, and 165 MPa, respectively. While they were lower than the alloys fabricated by atmospheric melting at high temperatures, such as at 400 °C (285 MPa), 450 °C (266 MPa), and 500 °C (230 MPa), which could be explained by the grain boundaries strengthening of refined grains. At room temperature, the studied alloy fabricated by SPS had many refined grains, resulting in high tensile strength. However, the grain-refined/coarsened boundaries became the crack sources and the crack propagation paths, which were not conducive to the high-temperature strength. These findings are helpful in developing high heat-resistant Cu–Cr–Nb alloys. • Cu–Cr–Nb alloys were fabricated by atmospheric melting and spark plasma sintering. • The alloy fabricated by atmospheric smelting had higher high-temperature tensile strength. • Room-temperature strengthening and high-temperature failure mechanisms were discussed. • Machine learning was further applied to the design of colorful copper alloys.