“…The protective character of a-Al 2 O 3 scale and its adherence to the substrate can be improved through the use of reactive elements (RE), e.g., Zr, Hf, Y, Ce, La, and other rare earth elements) [1,[8][9][10][11][12][13]. The required RE concentration in the scale depends on several factors such as the chemical composition of the alloy, the amount and kind of impurities (e.g., sulfur) the latter contains, the kind of reactive element and the oxidation conditions (temperature, time, environment).…”