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[charlie T colton]

High-entropy alloys (HEAs)

Thanks Rainbow7. The subject of your post follows.

First demonstration of promising selective electron beam melting method for utilizing high-entropy alloys as engineering materials

Highlights
• We succeeded in applying selective electron beam melting to the AlCoCrFeNi high-entropy alloy.
• The mechanical properties of the molds were far superior to those of the corresponding castings.
• The ductility in particular was remarkably enhanced by selective electron beam melting.
• The fracture strength was above 1400 MPa, which was more than six times higher than that of SUS304.

Abstract
High-entropy alloys (HEAs) are equiatomic, multi-element systems that contain five or more principal elements and have unique and excellent properties. However, it is difficult to overcome the inherent complexity and high levels of control required to produce homogeneous alloys industrially using a conventional casting method. We applied an additive manufacturing technique involving the use of selective electron beam melting (SEBM), which can facilitate a high level of local process control and generate rapid solidification cooling rates. The mechanical properties of the equiatomic AlCoCrFeNi HEA molds produced by SEBM were far superior to those of the corresponding castings. The ductility in particular was remarkably improved. The fracture strength was above 1400 MPa, which was more than six times higher than that of SUS304, a conventional engineering material. We succeeded in demonstrating for the first time that SEBM is a promising manufacturing process for utilizing HEAs as engineering materials.


Good stuff. Take a look at who else has been working on it.

Rolls-Royce UTC -- Department of Materials Science and Metallurgy

High-Entropy Alloys

High Entropy Alloys (HEAs) are an intriguing new class of metallic materials, based on a novel approach to materials design. Contrary to conventional alloying, these materials do not have a principal component, but are instead based on near equiatomic mixtures of five or more elements. Traditional metallurgical wisdom would expect the microstructure of these materials to contain a number of intermetallic phases, yet surprisingly, this has not to been the case. Experimental studies have reported single or dual phase as-cast microstructures, and corresponding diffraction data have indicated that these phases have simple crystal structures, such as fcc or bcc.



To rationalise these observations, it was suggested that entropy of mixing in these systems must be very high, extending the mutual solubility of different elemental species and stabilising simple structured solid solutions with respect to the formation of intermetallic compounds. Studies of such alloys have identified a number of promising properties, including high strength, good wear characteristics and excellent corrosion resistance, which make these materials industrially relevant. However, despite a huge number or research articles having been published in this area in the last ten years, much of the underlying science of these materials remains under debate.

Within the UTC, our work focuses on two main areas; 1) gaining a fundamental understanding of the phase metallurgy of near equiatomic HEAs, and 2) developing novel alloys based on the HEA concept for use at elevated temperature.