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Exploration and Development of High Entropy Alloys for Structural Applications
AF Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson AFB, Dayton, OH 45433, USA
* Author to whom correspondence should be addressed.
Received: 31 October 2013; in revised form: 27 November 2013 / Accepted: 20 December 2013 / Published: 10 January 2014
Abstract: We develop a strategy to design and evaluate high-entropy alloys (HEAs) for structural use in the transportation and energy industries. We give HEA goal properties for low (≤150 °C), medium (≤450 °C) and high (≥1,100 °C) use temperatures. A systematic design approach uses palettes of elements chosen to meet target properties of each HEA family and gives methods to build HEAs from these palettes. We show that intermetallic phases are consistent with HEA definitions, and the strategy developed here includes both single-phase, solid solution HEAs and HEAs with intentional addition of a 2nd phase for particulate hardening. A thermodynamic estimate of the effectiveness of configurational entropy to suppress or delay compound formation is given. A 3-stage approach is given to systematically screen and evaluate a vast number of HEAs by integrating high-throughput computations and experiments. CALPHAD methods are used to predict phase equilibria, and high-throughput experiments on materials libraries with controlled composition and microstructure gradients are suggested. Much of this evaluation can be done now, but key components (materials libraries with microstructure gradients and high-throughput tensile testing) are currently missing. Suggestions for future HEA efforts are given.
Keywords: structural metals; high-entropy alloys (HEAs); alloy design; high-throughput
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Miracle, D.B.; Miller, J.D.; Senkov, O.N.; Woodward, C.; Uchic, M.D.; Tiley, J. Exploration and Development of High Entropy Alloys for Structural Applications. Entropy 2014, 16, 494-525.
Miracle DB, Miller JD, Senkov ON, Woodward C, Uchic MD, Tiley J. Exploration and Development of High Entropy Alloys for Structural Applications. Entropy. 2014; 16(1):494-525.
Miracle, Daniel B.; Miller, Jonathan D.; Senkov, Oleg N.; Woodward, Christopher; Uchic, Michael D.; Tiley, Jaimie. 2014. "Exploration and Development of High Entropy Alloys for Structural Applications." Entropy 16, no. 1: 494-525.