Stresses in alumina scales on NiCrAlY-alloys determined by XSE and LRS

The effect of silicon and titanium on the spallation resistance of alumina scales grown on NiCrAlY-type alloys has been investigated. For this purpose cyclic oxidation experiments on model alloys with different additions of silicon or titanium were carried out at temperatures between 950 and 1100 °C. Selected samples were analysed by X-ray stress evaluation (XSE) after various times of oxidation. It was found that the compressive stresses measured at ambient temperature increase with increasing time and are affected by the presence of silicon. The XSE results were used to calibrate laser Raman spectroscopy (LRS) for strain measurement. Then, the suitability of Raman spectroscopy for stress measurement at higher temperatures was evaluated.Dedicated to Professor Dr. rer. nat. Dr. h.c. Hubertus Nickel on to occasion of his 65th birthday