Influence of copper and aluminum substitution on high‐temperature oxidation of the FeCoCrNiMn "Cantor" alloy. Issue 1 (6th September 2022) - Bürckner, Mary‐Lee
Abstract: In this study, the oxidation behavior of FeCoCrNiMn (HEA + Mn) is compared to three modified HEAs manufactured by substituting Mn with Al, Cu, or Al + Cu. Oxidation tests were conducted between 600°C and 800°C for up to 500 h in synthetic air. Substitution of Mn leads to a significant improvement in the oxidation resistance for the three modified HEAs. For FeCoCrNiCu (HEA + Cu), a local attack of a Cu‐rich phase was observed, leading to the formation of CuO blisters on the surface. The FeCoCrNiAl (HEA + Al) alloy was characterized by the formation of a thin Al2 O3 surface layer for all temperatures. However, for the HEA + Al alloy the formation of AlN was observed after 300 h at 800°C, leading to a partial breakdown of the protective scale. FeCoCrNiCuAl (HEA + Cu + Al) by far showed the best oxidation resistance, characterized by the formation of a highly protective Al2 O3 scale that effectively inhibited nitrogen penetration into the metal subsurface and local attack of the Cu‐rich phase. Abstract : The oxidation behavior of FeCoCrNiMn‐based high‐entropy alloys was evaluated at 600–800°C for 100–500 h of exposure to synthetic air. Substitution of Mn by Cu led to significantly enhanced oxidation resistance, which could be further improved by the addition of Al.