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Bowden D, Krysiak Y, Palatinus L, Tsivoulas D, Plana-Ruiz S, Sarakinou E, Kolb U, Stewart D, Preuss M. A high-strength silicide phase in a stainless steel alloy designed for wear-resistant applications. Nat Commun 2018; 9:1374. [PMID: 29636474 PMCID: PMC5893616 DOI: 10.1038/s41467-018-03875-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 03/20/2018] [Indexed: 11/09/2022] Open
Abstract
Hardfacing alloys provide strong, wear-resistant and corrosion-resistant coatings for extreme environments such as those within nuclear reactors. Here, we report an ultra-high-strength Fe-Cr-Ni silicide phase, named π-ferrosilicide, within a hardfacing Fe-based alloy. Electron diffraction tomography has allowed the determination of the atomic structure of this phase. Nanohardness testing indicates that the π-ferrosilicide phase is up to 2.5 times harder than the surrounding austenite and ferrite phases. The compressive strength of the π-ferrosilicide phase is exceptionally high and does not yield despite loading in excess of 1.6 GPa. Such a high-strength silicide phase could not only provide a new type of strong, wear-resistant and corrosion-resistant Fe-based coating, replacing more costly and hazardous Co-based alloys for nuclear applications, but also lead to the development of a new class of high-performance silicide-strengthened stainless steels, no longer reliant on carbon for strengthening.
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Affiliation(s)
- D Bowden
- School of Materials, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Y Krysiak
- Institute of Inorganic Chemistry and Analytical Chemistry, Johannes Gutenberg University Mainz, Jakob-Welder-Weg 11, 55099, Mainz, Germany
| | - L Palatinus
- Academy of Sciences of the Czech Republic, Institute of Physics, Na Slovance 2, 18040, Praha 8, Czech Republic
| | - D Tsivoulas
- School of Materials, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.,Wood plc, 601 Faraday Street, Birchwood Park, Warrington, WA3 6GN, UK
| | - S Plana-Ruiz
- Institute of Inorganic Chemistry and Analytical Chemistry, Johannes Gutenberg University Mainz, Jakob-Welder-Weg 11, 55099, Mainz, Germany.,LENS, MIND/IN2UB, Electronics and Biomedical Engineering, Faculty of Physics, University of Barcelona, Martí i Franquès, 1-11, 08028, Barcelona, Catalonia, Spain
| | - E Sarakinou
- School of Materials, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.,Interface Analysis Centre, University of Bristol, Bristol, BS8 1TL, UK
| | - U Kolb
- Institute of Inorganic Chemistry and Analytical Chemistry, Johannes Gutenberg University Mainz, Jakob-Welder-Weg 11, 55099, Mainz, Germany
| | - D Stewart
- Rolls-Royce plc, Derby, DE24 8BJ, UK
| | - M Preuss
- School of Materials, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
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Karagadde S, Lee PD, Cai B, Fife JL, Azeem MA, Kareh KM, Puncreobutr C, Tsivoulas D, Connolley T, Atwood RC. Transgranular liquation cracking of grains in the semi-solid state. Nat Commun 2015; 6:8300. [PMID: 26353994 PMCID: PMC4579839 DOI: 10.1038/ncomms9300] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 08/07/2015] [Indexed: 11/23/2022] Open
Abstract
Grain refinement via semi-solid deformation is desired to obtain superior mechanical properties of cast components. Using quantitative in situ synchrotron X-ray tomographic microscopy, we show an additional mechanism for the reduction of grain size, via liquation assisted transgranular cracking of semi-solid globular microstructures. Here we perform localized indentation of Al-15wt.%Cu globular microstructures, with an average grain size of ∼480 μm, at 555 °C (74% solid fraction). Although transgranular fracture has been observed in brittle materials, our results show transgranular fracture can also occur in metallic alloys in semi-solid state. This transgranular liquation cracking (TLC) occurs at very low contact stresses (between 1.1 and 38 MPa). With increasing strain, TLC continues to refine the size of the microstructure until the grain distribution reaches log-normal packing. The results demonstrate that this refinement, previously attributed to fragmentation of secondary arms by melt-shearing, is also controlled by an additional TLC mechanism. To obtain superior mechanical properties of cast components, grain refinement via semi-solid deformation is desirable. Here, the authors use in situ X-ray tomography to study the response of an alloy to indentation, and present a new mechanism of transgranular liquation cracking.
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Affiliation(s)
- S Karagadde
- Manchester X-ray Imaging Facility, School of Materials, The University of Manchester, Manchester M13 9PL, UK.,Research Complex at Harwell, Harwell Science &Innovation Campus, Didcot OX11 0FA, UK
| | - P D Lee
- Manchester X-ray Imaging Facility, School of Materials, The University of Manchester, Manchester M13 9PL, UK.,Research Complex at Harwell, Harwell Science &Innovation Campus, Didcot OX11 0FA, UK
| | - B Cai
- Manchester X-ray Imaging Facility, School of Materials, The University of Manchester, Manchester M13 9PL, UK.,Research Complex at Harwell, Harwell Science &Innovation Campus, Didcot OX11 0FA, UK
| | - J L Fife
- Swiss Light Source, Paul Scherrer Institut, Villigen PSI 5232, Switzerland
| | - M A Azeem
- Manchester X-ray Imaging Facility, School of Materials, The University of Manchester, Manchester M13 9PL, UK.,Research Complex at Harwell, Harwell Science &Innovation Campus, Didcot OX11 0FA, UK
| | - K M Kareh
- Department of Materials, Imperial College London, London SW7 2AZ, UK
| | - C Puncreobutr
- Department of Metallurgical Engineering, Chulalongkorn University, Bangkok 10330, Thailand
| | - D Tsivoulas
- Manchester X-ray Imaging Facility, School of Materials, The University of Manchester, Manchester M13 9PL, UK
| | - T Connolley
- Diamond Light Source Ltd, Harwell Science &Innovation Campus, Didcot OX11 0DE, UK
| | - R C Atwood
- Diamond Light Source Ltd, Harwell Science &Innovation Campus, Didcot OX11 0DE, UK
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