STRESSES IN ALUMINA SCALES ON NICRALY-ALLOYS DETERMINED BY XSE AND LRS

The effect of silicon and titanium on the spallation resistance of alu mina scales grown on NiCrAlY-type alloys has been investigated. For th is purpose cyclic oxidation experiments on model alloys with different additions of silicon or titanium were carried out at temperatures bet ween 950 and 1100 degrees C. Selected samples were analysed by X-ray s tress 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 s tress measurement at higher temperatures was evaluated.