Revealing the mechanism of the early stages of Ni–W RABiTS oxidation

• Published in: Journal of materials research Vol. 25; no. 12; pp. 2362 - 2370
• Main Authors: Blednov, Andrey V., Gorbenko, Oleg Yu, Rodionov, Dmitriy P., Kaul, Andrey R.
• Format: Journal Article
• Language: English
• Published: New York, USA Cambridge University Press 01-12-2010; Springer International Publishing
• Subjects: Applied and Technical Physics; Biomaterials; Inorganic Chemistry; Materials Engineering; Materials Science; Nanotechnology; Oxidation; Oxidation; W; Ni
• ISSN: 0884-2914; 2044-5326
• DOI: 10.1557/jmr.2010.0312

The early stages of surface oxidation of biaxially textured Ni–W tapes were studied using thermodynamic calculations along with experimental tape oxidation at low P(O2). Tape phase and chemical composition, surface morphology, and roughness were examined using x-ray diffraction (XRD), energy-dispersive x-ray analysis (EDX), secondary ion mass spectroscopy (SIMS), x-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). For a Ni0.95W0.05 alloy tape, the precise position of the tape oxidation line in P(O2)–T coordinates was established. This line includes a break at T ≈ 650 °C that originates from the change of the W oxidation mechanism from internal oxidation to oxidation on a free surface accompanied by segregation of the alloy components in the tape near-surface region. The surface roughness of a polished tape increased drastically during internal oxidation of W; further tape oxidation did not affect the integral roughness parameters, but introduced numerous small (˜;100 nm) features on the tape surface comprising NiO precipitates.