A Cu-Containing High-Entropy Alloy with High Corrosion Resistance and Low Surface Electrical Resistance

Abstract

Cu-base alloys with high corrosion resistance and low surface electrical resistance in corrosive environments were studied for application to electrical connectors. To achieve both high corrosion resistance and low surface electrical resistance, duplex alloys were fabricated.Non-equiatomic CuSnZnAlNi high-entropy alloys were prepared by induction melting. As raw materials, Cu-Zn alloy and pure metals of Sn, Al, and Ni were used. After casting, heat treatment was performed at 500 ℃ for 5 h (water-quenching). After that, the specimen surfaces were polished with a diamond paste down to 1 µm. The microstructure of the specimens was observed using an optical microscope and a field emission scanning electron microscope (FE-SEM) equipped with energy dispersive X-ray spectroscopy system (EDS). Electrochemical measurements were performed in synthetic seawater (pH 8.2) at 25 ℃. Dip-dry corrosion test was conducted. The specimens were dipped in synthetic seawater (pH 8.2) for 3.5 h and dried at 25 ℃ and 30 %RH for 0.5 h. Before and after the dip-dry corrosion test, surface electrical resistance was measured.Cu36Sn16Zn16Al16Ni16 was prepared, and the phases were identified by SEM/EDS. As a result, the alloys were separated into four phases. The corrosion resistance of each phase was compared by SEM/EDS between the specimens before polarization and the specimens after polarization and removal of corrosion products. 20 cycles of dip-dry corrosion test was conducted, with one cycle being the combination of immersion of the specimen in the solution and drying.