Impact of transition oxides on growth stresses and texture of alumina scales formed during oxidation of iron aluminides

The internal stresses and crystallographic texture in α-Al2O3 scales grown on iron aluminides at 1100 °C were determined in situ using synchrotron X-ray diffraction. In the first hour of oxidation, α-Al2O3 was formed by direct nucleation and by conversion from transition oxides (either θ-Al2O3 or a mixed Fe–Al oxide). A sharp texture develops connected with the direct nucleation of α-Al2O3, in contrast to the weaker texture observed in α-Al2O3 originated by previous transformations, which also yielded tensile stresses in early oxidation stages.