Differences in oxides morphology as a result of surface preparation of NiFe alloy

• Published in: Surface & coatings technology Vol. 385; p. 125421
• Main Authors: Serafin, Daria, Nowak, Wojciech J., Wierzba, Bartek
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15-03-2020; Elsevier BV
• Subjects: Diffusion; Diffusion barriers; Grain boundaries; High temperature; Internal oxidation; Iron compounds; Iron oxides; Morphology; Nickel base alloys; Nickel compounds; NiFe alloy; Oxidation; Oxidation resistance; Profilometers; Recrystallization; Sand-blasting; Sandblasting; Surface preparation; Surface roughness; Oxidation resistance; NiFe alloy; Diffusion; Internal oxidation; Surface preparation; Sand-blasting
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2020.125421

In this work, the influence of three different surface preparation processes, namely polishing, grinding and sand-blasting on oxidation process of high purity Ni48Fe52 alloy (in at. %) at high temperature has been investigated. Surface roughness of differently treated samples was measured by contact profilometer. Isothermal oxidation was performed in thermogravimetric furnace at 900°, 950° and 1000 °C for 24 h in air. Cross-sections were prepared and then observed and analyzed by SEM (Scanning Electron Microscope) /EDS (Energy Dispersive Spectroscopy). It was determined that sand-blasting increases the number of dislocations and grain boundaries in the near-surface region and therefore slows down oxidation process by faster formation of mixed nickel/iron oxide that constitutes a barrier for outward iron diffusion. Internally oxidized zone is also more uniform and thicker for polished and ground samples in comparison to sand-blasted ones as a result of recrystallization of the latter and longer duration of faster oxygen solubility in the polished and ground samples.
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•Surface of Ni48Fe52 alloy samples were polished, ground and sand-blasted.•Surface roughness was measured by contact profilometer.•Internal FeO precipitates are fine for polished and ground samples.•Internal FeO precipitates along grain boundaries are coarse for sand-blasted samples.•Sand-blasting prior to oxidation slows down the oxidation process.