Nano dual-phase CuNiTiNbCr high entropy alloy films produced by high-power pulsed magnetron sputtering

Dual-phase high entropy alloys have been proved to have the ability to overcome the strength-ductility trade-off. However, high-entropy alloy films are difficult to obtain a dual-phase structure due to the extremely high cooling rate during the preparation process and the high-entropy effect of the film itself. In this paper, the dual-phase CuNiTiNbCr high-entropy alloy films were prepared by high-power pulsed magnetron sputtering at different working pressures. The composition, microstructures, mechanical properties and electrochemical corrosion performance were tested by energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), nano-indentation, Vickers indentation and electrochemical polarization. The CuNiTiNbCr films exhibited a dual-phase structure composed of FCC matrix phase and Cu-rich BCC precipitated phase. The film presented a two-layer structure, the single FCC phase structure near the substrate and the FCC + BCC structure above. Comparing with FCC phase, the dual-phase structure exhibited higher hardness. With the increase of deposition pressure, the structure of the film became looser, and the hardness, toughness and corrosion resistance were all decreased due to the influence of the structure. It is proved that high-power pulsed magnetron sputtering is a feasible way for the phase structure regulation and performance improvement of high-entropy alloy films.