Synchrotron x-rays are used for in situ determination of oxide strain, during oxide
formation on a Kanthal A1 FeCrAlZr substrate at 1160°C. The measurements rely on use of high-energy (~80keV) x-rays and transmission geometry, and the methodology of the strain measurements is presented. Oxide growth strains at
elevated temperature, relative to pure alumina, were seen to be small, while temperature excursions induced significant strains. Furthermore, significant strain
relaxation was observed during isothermal holds, suggesting oxide creep as a major
relaxation mechanism. Upon cooling to room temperature, significant residual strains
developed, with a corresponding in-plane residual stress of -3.7 GPa.