Microstructure Formation and Oxidation Resistance of Laser-Cladding Al_3.63Co_10.58Cr_13.41Fe_51.28Mo_12.15Ni_8.95 Coating

In this work, Al_9.9Co_18.18Cr_18.18Fe_18.18Mo_18.18Ni_18.18 (at.%) high-entropy alloy was laser-cladded on the surface of H13 steel to extend the operating temperature range. Due to the dilution of substrate, coating with a composition of Al_3.63Co_10.58Cr_13.41Fe_51.28Mo_12.15Ni_8.95 (at.%) was achieved, which was a multi-phase system composed of FCC + BCC + σ + μ. Moreover, the phase transformation and the solidification behavior of the coating were studied in detail by utilizing phase diagram calculation. Oxidation resistance of the coating was also investigated and compared with that of H13 steel over temperature range of 600-800 °C. Both the coating and H13 steel show excellent oxidation resistance at 600 °C. After holding at 700 °C and 800 °C, the oxidation rate (the increment in oxide layer thickness per unit of time) of the coating is significantly smaller than that of H13 steel. It indicates that Al_3.63Co_10.58Cr_13.41Fe_51.28Mo_12.15Ni_8.95 coating has an advantage over H13 steel when oxidized over the temperature range of 700-800 °C. Based on the research in this work, the service temperature of H13 steel can be effectively extended by the Al_3.63Co_10.58Cr_13.41Fe_51.28Mo_12.15Ni_8.95 coating.