Scale growth process at 1473 K on unmodified and yttrium- or chromium-implanted β-NiAl
Résumé
Early oxidation of unmodified and yttrium-implanted or chromium-implanted β-NiAl intermetallic compound at 1473 K was studied using a combination of two-stage-oxidation exposure with 18O2 as a tracer, SIMS elemental distribution analysis (depth profiling and imaging modes) and photoluminescence spectroscopy analysis of the scale phase composition. It was found that phase transformation of transient aluminium oxides, represented by θ- Al2O3 into stable and protective α-Al 2O3 occurs locally and is affected by implanted additions: Yttrium retarded while chromium appeared to accelerate it. Typical patch- and/or web-like scale morphology of the growing scales was observed. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.