Processing and microstructure characterisation of oxide dispersion strengthened Fe–14Cr–0.4Ti–0.25Y2O3 ferritic steels fabricated by spark plasma sintering
journal contributionposted on 08.06.2015 by Hongtao Zhang, Yina Huang, Huanpo Ning, Ceri A. Williams, Andrew J. London, Karl Dawson, Zuliang Hong, Michael J. Gorley, Chris R.M. Grovenor, Gordon J. Tatlock, Steve G. Roberts, Michael J. Reece, Haixue Yan, Patrick S. Grant
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© 2015 The Authors. Ferritic steels strengthened with Ti–Y–O nanoclusters are leading candidates for fission and fusion reactor components. A Fe–14Cr–0.4Ti + 0.25Y2O3 (14YT) alloy was fabricated by mechanical alloying and subsequently consolidated by spark plasma sintering (SPS). The densification of the 14YT alloys significantly improved with an increase in the sintering temperature. Scanning electron microscopy and electron backscatter diffraction revealed that 14YT SPS-sintered at 1150 °C under 50 MPa for 5 min had a high density (99.6%), a random grain orientation and a bimodal grain size distribution (<500 nm and 1–20 μm). Synchrotron X-ray diffraction patterns showed bcc ferrite, Y2Ti2O7, FeO, and chromium carbides, while transmission electron microscopy and atom probe tomography showed uniformly dispersed Y2Ti2O7 nanoclusters of <5 nm diameter and number density of 1.04 × 1023 m−3. Due to the very much shorter consolidation times and lower pressures used in SPS compared with the more usual hot isostatic pressing routes, SPS is shown to be a cost-effective technique for oxide dispersion strengthened (ODS) alloy manufacturing with microstructural features consistent with the best-performing ODS alloys.
Acknowledgements This work was financially supported by the UK Engineering and Physical Sciences Research Council (EPSRC) under Grant EP/H018921/1. The authors would also like to thank the Diamond I11 beam line scientists Chiu Tang and Julia Parker, and further acknowledge financial support from EPSRC Grant EP/I012400/1 and Diamond proposal number 7528.
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