Microbeam plasma arc remanufacturing: Effects of Al on microstructure, wear resistance, corrosion resistance and high temperature oxidation resistance of AlxCoCrFeMnNi high-entropy alloy cladding layer

Abstract

In the study, the effects of Al content on the microstructure, wear resistance, corrosion resistance and high temperature oxidation resistance of CoCrFeMnNi high-entropy alloy cladding layer prepared by micro-beam plasma cladding process were studied in detail. The results showed that the microstructures of AlxCoCrFeMnNi high-entropy alloy cladding layer were dendritic structure, and when the content of Al in the alloy cladding layer was x ≤ 0.5, the cladding layer was still a single FCC phase; When x ≥ 1.0, the cladding layer was composed of two phases of FCC and BCC. The average microhardness and wear resistance of the cladding layer increased with the increase of Al content. The corrosion resistance of CoCrFeMnNi cladding layer was superior to that of 304 stainless steel. With the increase of Al content, the FCC phase in the cladding layer decreased, and the Al/Ni-rich BCC between the dendrites further increased, which formed numerous tiny primary cells between the two phases, so the increase of Al content reduced the corrosion resistance of the cladding layer. At 900 °C high temperature oxidation, the outward diffusion of Mn in the cladding layer controlled the whole process, and the main component of the oxide film was a Mn-rich non-densified oxide. With the increase of Al content, a fine and dense Cr2O3/Al2O3 oxide film was formed at the bottom of the oxide film, reduced the oxidation rate, which reduced the overall thickness of the oxide film gradually and improved the high temperature oxidation resistance.