Novel Additively Manufactured Coatings for Plasma Performance

High entropy alloys (HEAs) with three or more elements in equal concentrations have been observed to provide excellent shielding to ionizing radiation. These alloys have unique combinations of functional properties such as extremely high hardness, work hardening capacity, elevated temperature strength, ductility, toughness, excellent wear resistance, and superior corrosion resistance, all which could make their use as plasma facing component (PFC) for fusion reactors ideal. The broad design space for HEAs, however, remains relatively unexplored and much work still needs to be done to identify producible alloys with the properties needed for PFCs. Manufacturing processes for making real world HEA components are also quite immature, and approaches used for conventional alloys are currently used by default. A novel tungsten-based HEA was recently shown by scientists at LANL to be able to withstand unprecedented amounts of radiation without damage. This material, created as a thin film, is a quaternary nanocrystalline W-Ta-V-Cr alloy. The HEA retained outstanding mechanical properties after irradiation, and could be an excellent HEA for use as PFCs. To manufacture this HEA coating, a novel, in-situ process will be developed simultaneously. The in-situ HEA coating technology developed will also serve as the foundation for powerful and versatile new method to manufacture a wide array of HEA coatings with countless elemental combinations. In collaboration with LANL, the Phase I work will demonstrate the potential of the new HEA coating for PFCs. A unique process combination of high pressure cold spray (CS) and laser surface melting (LSM) will be used. Once deposited, the fundamental microstructure of the coatings will be evaluated, and then mechanical testing will be conducted to obtain properties data. The Phase I work will also develop computational models to identify potential HEA compositions for PFCs and their expected properties, conduct manufacturing process parameter development, and perform microstructural characterization and mechanical testing on the coatings for properties data. HEAs are expected to lead to breakthrough advances and superior performance in a wide array of applications across the aerospace, defense, automotive, energy, medical device, and electronics sectors, among others. Their value often lies in the potential to offer a suite of material properties tailored to a specific application rather than superior material performance according to only a single metric. For example, a high entropy steel alloy could simultaneously provide both high elongation to fracture and high ultimate tensile strength, a highly sought combination of properties for many industries including automotive and aerospace. High entropy alloys also excel in maintaining mechanical properties at both very high and very low temperatures; providing exceptional strength per weight, toughness, hardness, and corrosion resistance; and realizing challenging functional characteristics, such as magnetic, caloric, and electronic properties.