Microstructure Evolution of Gas-Atomized Iron-Base Ods Alloys

TitleMicrostructure Evolution of Gas-Atomized Iron-Base Ods Alloys
Publication TypeJournal Article
Year of Publication2010
AuthorsRieken JR, Anderson IE, Kramer MJ
Journal TitleInternational Journal of Powder Metallurgy
Volume46
Pages17-31
Date Published11
ISBN Number0888-7462
Accession NumberISI:000285430100006
KeywordsFERRITIC ALLOYS, stability, steels, TI
Abstract

In a simplified process to produce precursor powders for oxide dispersion-strengthened (ODS) alloys, gas-atomization reaction synthesis (GARS) was used to induce a surface oxide layer on molten droplets of three differing erritic stainless steel alloys during break-up and rapid solidification. The chemistry of the surface oxide was identified using auger electron spectroscopy (AES) and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). The precursor iron-base powders were consolidated at 850 C and 1,300 C using hot isostatic pressing (HIPing). Consolidation at the lower temperature resulted in a fully dense microstructure, while preventing substantial prior-particle-boundary-oxide dissociation. Microstructural analysis of the alloys consolidated at the higher temperature confirmed a significant reduction in prior-particle-boundary-oxide volume fraction, in comparison with the lower-temperature-consolidated sample. This provided evidence that a high-temperature internal oxygen-exchange reaction occurred between the metastable prior-particle-boundary-oxide phase (chromium oxide) and the yttrium contained within each prior particle. This internal oxygen-exchange reaction is shown to result in the formation of yttrium-enriched oxide dispersoids throughout the alloy microstructure. The evolving microstructure was characterized using transmission electron microscopy (TEM) and high-energy X-ray diffraction (HE-XRD).

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Alternate JournalInt J Powder Metall