Enhanced wear and corrosion resistance of ultra-high-speed laser cladding AlFeCrNiCu high-entropy alloys by Ti doping

AlFeCrNiCuTi x (x=0, 0.5, 1.0 and 2.0 molar ratio) high-entropy alloy (HEA) coatings were prepared via ultra-high speed laser cladding (UHSLC). Their microstructural morphologies were systematically analyzed. The mechanical properties of the coatings including microhardness and wear properties were evaluated. The corrosion behavior was evaluated by a potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS). The results show that the phase composition of the coating transformed from BCC1 + α to BCC1 + BCC2 + Laves phases with the addition of Ti. The Ti element promoted the crystal structure transition from columnar crystals to equiaxed crystals. The microhardness of the coating increased to 755.97±17.4 HV 0.2 with the Ti content increasing to 1.0 due to BCC solid solution strengthening. The wear rates of the AlFeCrNiCuTi 2.0 coating were reduced to 2.65 × 10 -6 mm 3 ·N -1 ·m -1 due to the composite structure with BCC and Laves phases. The AlFeCrNiCuTi 0.5 coating had the best corrosion resistance with the corrosion potential of -0.21 V and the corrosion current density of 5.99 × 10 -7 A·cm −2 due to a stable passive film dominated by Ti and Cr oxides.