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High-pressure high-temperature tailoring of High Entropy Alloys for extreme environments

DOI: 10.1016/j.jallcom.2017.12.216 DOI Help

Authors: Kirill V. Yusenko (Swansea University; Institute of Solid State Chemistry) , Sephira Riva (Swansea University) , Wilson A. Crichton (ESRF – The European Synchrotron) , Kristina Spektor (ESRF – The European Synchrotron) , Elena Bykova (Deutsches Elektronen-Synchrotron) , Anna Pakhomova (Deutsches Elektronen-Synchrotron) , Adam Tudball (Kennametal Manufacturing (UK) Ltd) , Ilya Kupenko (Institut für Mineralogie, Westfälische-Wilhelms-Universität Münster) , Arno Rohrbach (Institut für Mineralogie, Westfälische-Wilhelms-Universität Münster) , Stephan Klemme (Institut für Mineralogie, Westfälische-Wilhelms-Universität Münster) , Francesco Mazzali (Swansea University) , Serena Margadonna (Swansea University) , Nicholas P. Lavery (Swansea University) , Stephen G. R. Brown (Swansea University)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Journal Of Alloys And Compounds , VOL 738 , PAGES 491 - 500

State: Published (Approved)
Published: March 2018
Diamond Proposal Number(s): 13987

Abstract: The exceptional performance of some High Entropy Alloys (HEAs) under extreme conditions holds out the possibility of new and exciting materials for engineers to exploit in future applications. In this work, instead of focusing solely on the effects of high temperature on HEAs, the effects of combined high temperature and high pressure were observed. Phase transformations occurring in a pristine HEA, the as-cast bcc–Al2CoCrFeNi, are heavily influenced by temperature, pressure, and by scandium additions. As-cast bcc–Al2CoCrFeNi and fcc–Al0.3CoCrFeNi HEAs are structurally stable below 60 GPa and do not undergo phase transitions. Addition of scandium to bcc–Al2CoCrFeNi results in the precipitation of hexagonal AlScM intermetallic (W-phase), which dissolves in the matrix after high-pressure high-temperature treatment. Addition of scandium and high-pressure sintering improve hardness and thermal stability of well-investigated fcc- and bcc- HEAs. The dissolution of the intermetallic in the main phase at high pressure suggests a new strategy in the design and optimization of HEAs.

Journal Keywords: High-entropy alloys; Scandium; High-pressure high-temperature sintering; Spark plasma sintering; In situ X-ray diffraction

Subject Areas: Materials, Engineering


Instruments: I11-High Resolution Powder Diffraction

Other Facilities: PETRA III - DESY; European Synchrotron Radiation Facility