Phase compositions and properties of NbMoTaVTi refractory high-entropy alloy coating on Ti-6Al-4V alloy

To improve the properties of TC4 alloy, NbMoTaVTi refractory high-entropy alloy coating without defects was successfully prepared on the surface of TC4 alloy by laser cladding method. Phase compositions and properties were investigated through various characterization methods. The coating exhibited a dual-phase structure of BCC and HCP. SEM and EDS showed that the coating formed an excellent metallurgical bond with the TC4 substrate and had a small heat-affected zone. The microhardness of the coating was 600.62 HV, which was 57.63 % higher than the microhardness of the substrate. High-temperature experiments at 1000 °C, 1100 °C, 1200 °C revealed that the coating had better oxidation resistance at high temperatures. An electrochemical experiment in 3.5 wt% NaCl solution showed that the passive film's stability on the coating's surface was improved. The corrosion rates of the substrate and coating were 258.10 × 10⁻³ mpy and 87.79 × 10⁻³ mpy, respectively, indicating that the coating had better corrosion resistance.