Atomistic clustering-ordering and high-strain deformation of an Al0.1CrCoFeNi high-entropy alloy

Abstract

Computational investigations of structural, chemical, and deformation behavior in high-entropy alloys (HEAs), which possess notable mechanical strength, have been limited due to the absence of applicable force fields. To extend investigations, we propose a set of intermolecular potential parameters for a quinary Al-Cr-Co-Fe-Ni alloy, using the available ternary Embedded Atom Method and Lennard-Jones potential in classical molecular-dynamics simulations. The simulation results are validated by a comparison to first-principles Korringa-Kohn-Rostoker (KKR) - Coherent Potential Approximation (CPA) [KKR-CPA] calculations for the HEA structural properties (lattice constants and bulk moduli), relative stability, pair probabilities, and high-temperature short-range ordering. The simulation (MD)-derived properties are in quantitative agreement with KKR-CPA calculations (first-principles) and experiments. We study AlxCrCoFeNi for Al ranging from 0 ≤ x ≤2 mole fractions, and find that the HEA shows large chemical clustering over a wide temperature range for x < 0.5. At various temperatures high-strain compression promotes atomistic rearrangements in Al0.1CrCoFeNi, resulting in a clustering-to-ordering transition that is absent for tensile loading. Large fluctuations under stress, and at higher temperatures, are attributed to the thermo-plastic instability in Al0.1CrCoFeNi.

Design of high-strength refractory complex solid-solution alloys

“…However, we find that adding Al stabilizes A2-phase up to 20%Mo, and similar behavior of Al-addition has been seen in other alloys too. 19 On the other hand, Si-addition comes out to be energetically less favorable than Al-addition. High-Throughput Assessments: For (Mo-W)-Ta-(Ti-Zr) results are most easily presented in a cut through 5D {c α } space to visualize with only two parameters (x, y) along lines or planes ( Fig.…”

“…As an alloying guide, SRO identifies pairs driving the instability, and predicts the spinodal T sp , where α −1 µν (k 0 ; T sp )=0 signifying the absolute instability to this chemical fluctuation. 18,19 In real-space, pair probabili- Fig. 5 have maximal SRO peaks in α µν (k 0 =Γ;T>T sp ) signaling spinodal (infinite wavelength) decomposition in specified pairs at T sp of 1240 K for C1, and at 500 K for C6.…”

“…The spinodal temperature, where α −1 µν (k0; Tsp)=0, signifies an absolute instability to this fluctuation and provides an estimate for T M G c or T od c . 18,19,58 For N>2, pairs driving ordering (clustering) will not necessarily be the same pairs that peak in the SRO due to the matrix inversion that relates them (Fig. 5).…”

A Combinatorial Approach for Assessing the Magnetic Properties of High Entropy Alloys: Role of Cr in AlCoxCr1–xFeNi

“…At room temperature, homogenized Al x CoCrFeNi alloys for x = 0.5, 1.25 and 2 exhibit ferromagnetic behaviour, while for x = 0, 0.25 and 0.75, they are paramagnetic in nature. AlxCrCoFeNi HEA shows large chemical clustering over a wide temperature range for x < 0.5 . Over a range of temperatures, high‐strain compression promotes atomistic rearrangements in Al 0.1 CrCoFeNi, resulting in a clustering‐to‐ordering transition.…”

Investigation of the phase stabilities in AlNiCoCrFe high entropy alloys

“…There have been various attempts to validate existing models/databases by correlating experimental results with those derived computationally. These modeling attempts include comparisons with empirically determined rules, termed the HEA phase formation rules [8,[12][13][14][31][32][33][34][35][36][37][38][39][40], ab-initio based methods [41][42][43][44][45][46][47], and thermodynamic calculations based on the CALPHAD (CALculation of PHAse Diagrams) method [36,[48][49][50][51][52][53]. The CALPHAD method has evolved over the past 30 years and has become widely utilized in the scientific community due to its simplicity, computational efficiency, and reasonable agreement with experimental data [36,50,51].…”