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Metals 2016, 6(5), 106;

Formation and Disruption of W-Phase in High-Entropy Alloys

College of Engineering, Swansea University, Bay Campus, Swansea SA1 8EN, Wales, UK
Centre of Nanohealth, Swansea University, Singleton Park, Swansea SA2 8PP, Wales, UK
Sustainable Product Engineering Centre for Innovative Functional Industrail Coatings (SPECIFIC), Baglan Bay Innovation & Knowledge Centre, Central Avenue, Baglan, Port Talbot SA12 7AX, Wales, UK
Authors to whom correspondence should be addressed.
Academic Editor: Soran Birosca
Received: 1 April 2016 / Revised: 26 April 2016 / Accepted: 29 April 2016 / Published: 6 May 2016
(This article belongs to the Special Issue Process-Structure-Property Relationships in Metals)
View Full-Text   |   Download PDF [7053 KB, uploaded 6 May 2016]   |  


High-entropy alloys (HEAs) are single-phase systems prepared from equimolar or near-equimolar concentrations of at least five principal elements. The combination of high mixing entropy, severe lattice distortion, sluggish diffusion and cocktail effect favours the formation of simple phases—usually a bcc or fcc matrix with minor inclusions of ordered binary intermetallics. HEAs have been proposed for applications in which high temperature stability (including mechanical and chemical stability under high temperature and high mechanical impact) is required. On the other hand, the major challenge to overcome for HEAs to become commercially attractive is the achievement of lightweight alloys of extreme hardness and low brittleness. The multicomponent AlCrCuScTi alloy was prepared and characterized using powder X-ray diffraction (PXRD), scanning-electron microscope (SEM) and atomic-force microscope equipped with scanning Kelvin probe (AFM/SKP) techniques. Results show that the formation of complex multicomponent ternary intermetallic compounds upon heating plays a key role in phase evolution. The formation and degradation of W-phase, Al2Cu3Sc, in the AlCrCuScTi alloy plays a crucial role in its properties and stability. Analysis of as-melted and annealed alloy suggests that the W-phase is favoured kinetically, but thermodynamically unstable. The disruption of the W-phase in the alloy matrix has a positive effect on hardness (890 HV), density (4.83 g·cm−3) and crack propagation. The hardness/density ratio obtained for this alloy shows a record value in comparison with ordinary heavy refractory HEAs. View Full-Text
Keywords: metals and alloys; phase transformations; high-entropy alloys; scandium; W-phase; Al2Cu3Sc metals and alloys; phase transformations; high-entropy alloys; scandium; W-phase; Al2Cu3Sc

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Riva, S.; Fung, C.M.; Searle, J.R.; Clark, R.N.; Lavery, N.P.; Brown, S.G.R.; Yusenko, K.V. Formation and Disruption of W-Phase in High-Entropy Alloys. Metals 2016, 6, 106.

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