Correlation analysis of strongly fluctuating atomic volumes, charges, and stresses in body-centered cubic refractory high-entropy alloys

Abstract

Local lattice distortions in a series of body-centered cubic alloys, including refractory high-entropy alloys, are investigated by means of atomic volumes, atomic charges, and atomic stresses defined by the Bader charge analysis based on first-principles calculations. Analyzing the extensive data sets, we find large distributions of these atomic properties for each element in each alloy, indicating a large impact of the varying local chemical environments. We show that these local-environment effects can be well understood and captured already by the first and the second nearest neighbor shells. Based on this insight, we employ linear regression models up to the second nearest neighbor shell to accurately predict these atomic properties. Finally, we find that the elementwiseaveraged values of the atomic properties correlate linearly with the averaged valence-electron concentration of the considered alloys.

Impact of N on the Stacking Fault Energy and Phase Stability of FCC CrMnFeCoNi: An Ab Initio Study

“…Atomic stresses in bcc refractory HEAs are also well predicted based on the local VEC around the atoms. [84] Indeed, the correlation coefficients of DE sol and the local VEC in the 1NN shell are found to be 0.845 and 0.848 for the fcc and the hcp phases, respectively, indicating strong correlations with DE sol and the local VEC. These correlation coefficients for N in CrMnFeCoNi are much larger than those for C in CrMnFeCoNi obtained previously (0.511 and 0.597 for the fcc and the hcp phases, respectively).…”

A Review of the Latest Developments in the Field of Refractory High-Entropy Alloys

“…An (NbTiZr)X alloy showed satisfactory results that matched the practical results [22], and, by using the first-principles calculation, elastic constant, modulus, and lattice parameter, the total energy of NbMoTaW and NbMoTaWV refractory high-entropy alloys was calculated [74]. The atomic properties were accurately predicted using bi-linear regression models [75], and some researchers have reported that iterative MATLAB could be used to design RHEAs. Using this method, Shafiei et al generated 40,000 alloys by changing the proportion of alloying elements in the HfMoNbTaTiVZr alloy system, and they concluded that the strength of the alloy increased with the addition of zirconium and molybdenum and decreased with the addition of titanium.…”

<i>Ab Initio</i> Local-Energy and Local-Stress Calculations for Materials Science and Engineering

“…The authors discussed the relation between the atomic-stress fluctuation and the yield property of the alloys. 76) On the other hand, Ishibashi and co-workers 77) have applied our local-stress scheme to bcc HEAs consisting of refractory TM elements, and observed similar correlation between the atomic stress and charge transfer, while they observed that the results by the Bader partitioning can represent the effects of local chemical environments more reasonably, than those by the Voronoi partitioning, by incorporating the effects of realistic charge distribution between different species. The atomic charge, atomic volume and atomic stress of each constituent atom, defined by the Bader partitioning, show clear mutual correlation, which can be explained by the features of the valence electron concentration (VEC) of each atom and its first and second neighbor shells.…”

“…The atomic charge, atomic volume and atomic stress of each constituent atom, defined by the Bader partitioning, show clear mutual correlation, which can be explained by the features of the valence electron concentration (VEC) of each atom and its first and second neighbor shells. 77) The issue of the partitioning methods is discussed again in Sec. 5.…”

“…As for the machine-learning based interatomic potentials, a modified version 97) of the ab initio local-energy scheme 37) was also used for a neural-network force field of amorphous Si. 98) As for local stresses, machine-learning techniques were applied to find the correlation between an atomic stress and a local chemical environment in refractory HEAs, 77) where VEC features of each atom and its neighboring shells were found to decide the atomic stress as mentioned in Sec. 3.4.…”