Effect of yttria particle size on the microstructure and compression creep properties of nanostructured oxide dispersion strengthened ferritic (Fe–12Cr–2W–0.5Y2O3) alloy

In the present paper, microstructural characterization and compression creep properties of nanostructured ferritic oxide dispersion strengthened alloys (Fe–12Cr–2W–0.5Y2O3 (in wt.%)) synthesized by mechanical alloying and vacuum hot pressing are presented. In particular, the effect of starting yttria particle size (20 nm and 45 μm before mechanical alloying) on microstructure and creep properties was investigated. Study of compression creep properties (at 800 °C and 900 °C) revealed that the ODS alloy with finer dispersoids showed higher creep resistance. Grain growth was not very significant following creep testing at 800 °C (from ∼300 nm in hot pressed condition to ∼550 nm following creep at 800 °C). Analysis of stress exponents indicates that dislocation creep is the dominant deformation mechanism at 800 °C and 900 °C.

Norton plot showing strain rate vs. true stress for ODS-n, ODS-m, Fe–12Cr–2W–0.25Y2O3 (12YW) and Fe–14Cr–3W–0.4Ti–0.25Y2O3 (14YWT) alloys.Figure optionsDownload as PowerPoint slideHighlights
► Effect of starting yttria size on mechanical alloying, creep properties of ferritic steel studied.
► Compression creep results revealed that the ferritic nano-ODS alloy has higher creep resistance.
► Nano yttria particles contribute to the pinning of grain boundaries and improve creep properties.