| Abstract Scope |
The oxidation of FeCrNi medium entropy alloy is investigated from 700 to 1000°C by combining experimental observations with density functional theory (DFT) calculations. The sole oxidation product formed is Cr2O3. At 900°C, the layer exhibits a desirable density and continuity, attributed to the rapid diffusion of Cr facilitated by the body-centered cubic phase transformation. There is a significant increase in mass gain rates at 1000°C, accompanied by formation of a discontinuous Cr2O3 layer and penetration of oxide. These observations emphasized the significant roles of phase structure in promoting formation of protective oxide scale and influencing oxidation resistance. Moreover, the hot corrosion of FeCrNi and FeCrNiCoMn under Na2SO4/NaCl at 700–900°C is investigated, and compared to two commercial alloys. It was found that for alloy design, it's recommended to avoid using Mn due to high corrosion activity, and reduce the contents of Fe and Ni to regulate the formation of unprotective corrosion layers and prevent alloy decomposition. |