Atomic-scale distorted lattice in chemically disordered equimolar complex alloys

Pressure-induced phase transition in the AlCoCrFeNi high-entropy alloy

“…This result is consistent with the previous theoretical studies that the lattice distortion effect is more significant in the bcc-than the fcc-structured HEAs and the local lattice distortion is sensitive to pressure [20,21]. In an effective elastic medium model of chemically disordered equimolar complex alloys proposed by Ye et al, the atomic scale lattice distortion are revealed to build up a non-symmetric residual strain field with atomic scale fluctuations [23], and this kind of non-symmetric residual strain field is usually regarded as a direct cause to induce a potential phase transition.…”

“…[17] Therefore, many efforts have been made to address their extraordinary structural stability [16,18]. So far, the structural stability of HEAs is believed to be strongly associated with the deliberately maximized configurational entropy from a thermodynamic point of view, and also the kinetic factor of extremely sluggish atomic diffusion caused by the chemical-complexity induced packing disorder and considerable local lattice distortion [13,14,[19][20][21][22][23].…”

On Lattice Distortion in High Entropy Alloys

“…As a result, a local volumetric strain field arises due to the change of the atom size. Recently, Ye et al refined the geometric model by taking account of atomic displacement (Ye et al, 2018). In this new model, both volumetric and shear strains are derived and the model predictions agree quite well with the results of the first principles calculations.…”

“…Physically, one can reason that lattice distortion becomes generically favorable if E 1 < E 2 or unfavorable if E 1 > E 2 . To validate the above thinking, Ye et al very recently carried out extensive density functional theory (DFT) calculations on a series of equal-molar binary to quinary chemical complex alloys (Ye et al, 2018). An ideal FCC lattice without distortion was firstly constructed by allowing the atoms to expand or contract in order to reach a local energy minimum.…”

“…Apart from the above experimental efforts, a number of lattice distortion models (Zhang et al, 2008;Ye et al, 2015Ye et al, , 2016aYe et al, , 2018 were also developed either on a semi-empirical basis or in the light of atomistic simulations (Toda-Caraballo et al, 2015;Oh et al, 2016;Ye et al, 2018) and ab initio calculations (Song et al, 2017). In conventional alloys or dilute solid solution, lattice distortion and the resultant residual strain field can be derived by treating solute atoms as "inclusions" embedded into a "matrix" made up of solvent atoms (Eshelby, 1956(Eshelby, , 1957(Eshelby, , 1959.…”