Isothermal High Temperature Oxidation of Cantor’s-Based MC-Reinforced HEAs Versus Their Mn and Cr Contents

The behaviors in oxidation at high temperatureHigh temperature of a cast Cantor’s alloy, and of its derived versions involving MC carbidesMC carbides for mechanical reinforcement purpose, are characterized by external and internal corrosionCorrosion products which are multi-constituted, due to the involvement of manganeseManganese in addition to chromiumChromium. In this work, content decrease in Mn content was tested simultaneously with increase in Cr content to observe, with thermogravimetry follow-up and metallography characterizationCharacterization, how the isothermal mass gain kineticsKinetics at several high temperaturesHigh temperature in the [1000–1100 °C] are influenced by such changes of the chemical composition. The isothermal kineticsKinetics stay parabolic but become much slower, and the Kp values much lower but still above the ones obtained with really chromia-forming alloys. Despite the significant increase from 1 to 3 of the atomic contents Cr/Mn ratio to 3, Mn still interferes with the chromia formation. However chromia which formed as discontinuous oxides at the scale/alloy interface in the case of the original equimolar-type alloys, is now thin but continuous.