Effect of Zirconium Doping on Oxidation of Single Crystal β-NiAl

Relatively new optical techniques are utilized to study the oxidation of low-index crystal faces of a zirconium doped single crystal β-NiAl. With these non-destructive techniques residual stress, phase composition and thickness of the scales were determined at various temperatures. The results are compared with the results obtained from an undoped counterpart. Interesting differences in scale stress, thickness and phase composition have been observed. The residual stress evolves rather differently than that on the undoped counterpart. Initial lower stress levels in the doped crystal convert to higher stresses at higher oxidation temperatures. The orientation dependence and a stress anomaly observed with the undoped single crystal β-NiAl are still present on the doped sample. Fluorescence and Raman results indicate a higher concentration of θ-Al2O3 on all crystallographic phases with Zr doping. The oxide scales are also thinner on the Zr doped specimen.