A combined approach: Isotopic exposure/SIMS analysis/SEM to Study the Early Stages of oxidation of β-NiAl at 1473 K

摘要: The early oxidation stages of unmodified and yttrium-implanted β-NiAl have been studied at 1473 K using sequential isotopic exposure (so-called two-stage oxidation) combined with low high resolution SIMS analysis SEM characterization. The scales growing on material comprised typically a cracked morphology oxide ridges outward from the cracks. Some were formed reaction temperature during first stage continued second stage. This resulted in network outer surface scale. Two regions: non-cracked areas round patches observed scale β-NiAl. No but thin lace-like was cracks particles extruded some crack centres. by oxide. Inward oxygen transport contributed significantly to overall matter patches, while its contribution remaining much less pronounced. very outermost layer most enriched Cr, which present level ca. 90 ppm only starting material. finding is discussed terms effect Cr phase transformation unstable aluminas into stable β-Al2O3. The results showed that inhomogeneous regarding both composition microstructure. Therefore, analytical methods having respectable sensitivity might be used give reliable information growth mechanisms scales. applies as well electron microscopy methods. Ein gemeinsamer Ansatz: Isotopische Exposition/SIMS-Analyse/REM zur Untersuchung des Anfangsstadiums der Oxidation von β-NiAL bei K Das Anfangsstadium wurde an unmodifiziertem Material und nach Y-Implantation untersucht. Hierzu die 16O/18O-Zwei-Stufen-Oxidation Kombination mit hochauflosender Sekundarionenmassenspektrometrie (SIMS) sowie Rasterelektronenmikroskopie (REM) eingesetzt. Es zeigt sich, das gebildeten Oxidschichten hinsichtlich Zusammensetzung Gefuges nicht homogen sind. Deswegen war es erforderlich, analytische Methoden (SIMS REM) sehr hoher Ortsauflosung hochstmoglicher Empfindlichkeit zu verwenden. Dadurch konnten unterschiedlichen Wachstumsmechanismen den einzelnen Bereichen Oxidschicht auf beiden verschiedenen Substrattypen identifiziert werden.