Early oxidation stages of a Co-Cr-Fe-Mn-Ni-Si complex concentrated alloy with Cr, Mn, and Si contents matching those of 316L stainless steel

• CCA with Cr, Mn, and Si contents as 316 L, but 50 % higher configurational entropy. • At 400 °C spinel-type, corundum-type, and rock salt-type oxides form. • At 800 °C spinel-type and corundum-type oxides form, but spinel is dominant. • Configurational entropy does not dominate oxidation behavior. • Co and Ni are found in all oxide phases and favor spinel-type oxide formation. A complex concentrated Co-Cr-Fe-Mn-Ni-Si alloy with increased configurational entropy and contents of Cr, Mn, and Si corresponding to those in 316L stainless steel was studied with respect to its oxidation behavior. Early-stage oxidation was investigated for annealing at 400 °C and 800 °C. In addition to Cr, considerable amounts of Fe, Co, and Ni were found in the oxide, and nodules formed at 800 °C. In contrast to 316L, on which a protective corundum-type oxide forms during oxidation, the formation of spinel-type oxide was observed to dominate both at low and high temperature.