Abstract
This review paper provides insight into current developments in refractory high-entropy alloys (RHEAs) based on previous and currently available literature. High-temperature strength, high-temperature oxidation resistance, and corrosion resistance properties make RHEAs unique and stand out from other materials. RHEAs mainly contain refractory elements like W, Ta, Mo, Zr, Hf, V, and Nb (each in the 5–35 at% range), and some low melting elements like Al and Cr at less than 5 at%, which were already developed and in use for the past two decades. These alloys show promise in replacing Ni-based superalloys. In this paper, various manufacturing processes like casting, powder metallurgy, metal forming, thin-film, and coating, as well as the effect of different alloying elements on the microstructure, phase formation, mechanical properties and strengthening mechanism, oxidation resistance, and corrosion resistance, of RHEAs are reviewed.
Highlights
In day-to-day life, the demand for new materials is greatly expanding for various applications
Refractory elements like rhenium (Re), tungsten (W), molybdenum (Mo), tantalum (Ta), Niobium (Nb), and zirconium (Zr) are the main constituents of HEAs; along with them, other metals and materials are being used for the production of alloys named refractory high-entropy alloys (RHEAs)
These alloys consist of multiple elements, and multiple elements have different crystal structures, such as face-centered cubic (FCC), body-centered cubic (BCC), hexagonal close-packed (HCP), and intermetallic compounds (B2, L12, C14, and C15)
Summary
In day-to-day life, the demand for new materials is greatly expanding for various applications. Refractory elements like rhenium (Re), tungsten (W), molybdenum (Mo), tantalum (Ta), Niobium (Nb), and zirconium (Zr) are the main constituents of HEAs; along with them, other metals and materials are being used for the production of alloys named refractory high-entropy alloys (RHEAs). These alloys consist of multiple elements, and multiple elements have different crystal structures, such as face-centered cubic (FCC), body-centered cubic (BCC), hexagonal close-packed (HCP), and intermetallic compounds (B2, L12, C14, and C15). In Laves phases, the A type of atom occupies a diamond, hexagonal diamond, or related structure. This paper reviews recent developments in RHEAs, such as processing techniques, structural properties, welding, thin films, coatings, oxidation, corrosion behavior, and computational methods
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