Composition design and preparation process of refractory high-entropy alloys: A review

Bio-high entropy alloys: Progress, challenges, and opportunities

“…In 2010, Senkov et al ( Senkov et al, 2010 ) synthesized near-equivalent atoms WTaMoNb and WTaMoNbV alloys with single-phase body-centered cubic (BCC) lattice using the vacuum arc melting technique. Since then, many other HEAs based on refractory elements (Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W) have been the focus of experimental studies ( Gu P. et al, 2022 ; Chen S. H. et al, 2022 ; Huang et al, 2022 ; Peng et al, 2022 ; Zhou et al, 2022 ). The original RHEA was designed based on five refractory elements (Ta, Nb, Mo, W, and V).…”

“…These empirical parameters can distinguish solid solution from intermetallic compound phases, discriminate the formation of phases such as FCC/BCC/HCP, and predict the single-phase and multi-phase structures of HEAs [8]. The researchers have summarized a large amount of data and proposed some semi-empirical criteria for the formation of simple solid solutions: (1) The mixing entropy (ΔS mix) is 12–17.5 J/(molK), and the calculation formula of ΔS mix is ( Zhou et al, 2022 ): where R is the gas constant, and c i is the mole fraction of the i th element. (2) The mixing enthalpy (ΔH mix ) is −15–5 kJ/mol, and the calculation formula of ΔH mix is ( Zhou et al, 2022 ): where c j denotes the mole fraction of the j th element; H AB is the enthalpy of mixing between the A and B elements.…”

“…The researchers have summarized a large amount of data and proposed some semi-empirical criteria for the formation of simple solid solutions: (1) The mixing entropy (ΔS mix) is 12–17.5 J/(molK), and the calculation formula of ΔS mix is ( Zhou et al, 2022 ): where R is the gas constant, and c i is the mole fraction of the i th element. (2) The mixing enthalpy (ΔH mix ) is −15–5 kJ/mol, and the calculation formula of ΔH mix is ( Zhou et al, 2022 ): where c j denotes the mole fraction of the j th element; H AB is the enthalpy of mixing between the A and B elements. (3) The atomic size difference δ ≤ 6.5%, and the calculation formula of δ is ( Zhou et al, 2022 ): where r i denotes the atomic radius of the i th component; is the molar average atomic radius.…”

“… (2) The mixing enthalpy (ΔH mix ) is −15–5 kJ/mol, and the calculation formula of ΔH mix is ( Zhou et al, 2022 ): where c j denotes the mole fraction of the j th element; H AB is the enthalpy of mixing between the A and B elements. (3) The atomic size difference δ ≤ 6.5%, and the calculation formula of δ is ( Zhou et al, 2022 ): where r i denotes the atomic radius of the i th component; is the molar average atomic radius.…”

“…(1) The mixing entropy (ΔS mix) is 12–17.5 J/(molK), and the calculation formula of ΔS mix is ( Zhou et al, 2022 ):…”