High-temperature oxidation performance and corrosion resistance of laser cladded MoNbVTa0.5Six(x=0,0.5) refractory high-entropy alloys

This study investigated the performance differences between MoNbVTa0.5Six (x = 0,0.5) refractory high-entropy alloy coatings fabricated by laser cladding. The phase composition, high-temperature oxidation resistance, corrosion resistance, and microhardness of the coating were explicitly discussed. The phase composition indicates that both are composed of a main BCC phase, and MoNbVTa0.5Si0.5 also has a silicide phase. Due to the dense and uniform SiO2 oxide layer covering the coating surface, MoNbVTa0.5Si0.5 exhibits better oxidation resistance in high-temperature oxidation tests. The mass gain of MoNbVTa0.5Si0.5 is 7.11 mg center dot cm-2 at 800 degrees C, which is greater than that of MoNbVTa0.5 (5.24 mg center dot cm 2). But It is 68 mg center dot cm 2 and 67 mg center dot cm 2 at 1000 and 1200 degrees C, less than 73 mg center dot cm-2 and 71 mg center dot cm-2 of MoNbVTa0.5. The electrochemical test shows that the selfcorrosion current of MoNbVTa0.5Si0.5 is 0.030 mu A center dot cm-2, the self-corrosion current of MoNbVTa0.5 is 0.032 mu A center dot cm- 2. The results of microhardness tests show that the average hardness of MoNbVTa0.5Si0.5 is 772 HV, greater than that of MoNbVTa0.5 (743 HV).