Microstructure Evolution of Gas Atomized Iron Based ODS Alloys

Conference · Tue Dec 01 04:00:00 EST 2009

OSTI ID:1009067

Rieken, J R; Anderson, I E; Kramer, M J; Anderegg, J W; Shechtman, D

In a simplified process to produce precursor powders for oxide dispersion-strength- ened (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).

• Research Organization: Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
• Sponsoring Organization: USDOE
• OSTI ID: 1009067
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

36 MATERIALS SCIENCE
ALLOYS
AUGER ELECTRON SPECTROSCOPY
CHEMISTRY
CHROMIUM
DISSOCIATION
HOT PRESSING
IRON
MICROSTRUCTURE
OXIDES
PARTICULATES
POWDER METALLURGY
PRECURSOR
SCANNING ELECTRON MICROSCOPY
SOLIDIFICATION
SPECTROSCOPY
STAINLESS STEELS
SYNTHESIS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION
YTTRIUM