Mechanical Behavior of High-Entropy Alloys: A Review

Abstract

High-entropy alloys (HEAs) are materials that consist of equimolar or nearequimolar multiple principal components but tend to form single phases, which is a new research topic in the field of metallurgy, have attracted extensive attention in the past decade. The HEAs families contain the face-centered-cubic (fcc), body-centered-cubic (bcc), and hexagonal-close-packed (hcp)-structured HEAs. On one hand, mechanical properties, e.g. hardness, strength, ductility, fatigue, and elastic moduli, are essential for practical applications of HEAs. Scientists have explored in this direction since the advent of HEAs. On the other hand, the pursuit of high strength and good plasticity is the critical research issue of materials. Hence, strengthening of HEAs is a crucial issue. Recently, many articles are focusing on the strengthening strategies of HEAs [1][2][3][4][5][6][7][8][9][10][11][12][13][14].In this chapter, we reviewed the recent work on the room-temperature elastic properties and mechanical behavior of HEAs, including the mechanisms behind the plastic deformation of HEAs at both low and high temperatures. Furthermore, the present work examined the strengthening strategies of HEAs, e.g. strain hardening, grain-boundary strengthening, solid-solution strengthening, and particle strengthening. The fatigue, creep, and fracture properties were briefly introduced. Lastly, the future scientific issues and challenges of HEAs were discussed.

On the Stability of Complex Concentrated (CC)/High Entropy (HE) Solid Solutions and the Contamination with Oxygen of Solid Solutions in Refractory Metal Intermetallic Composites (RM(Nb)ICs) and Refractory Complex Concentrated Alloys (RCCAs)

“…single phase solid solution RHEAs TiZrNbMo (142 GPa), TiZrNbMoV (141 GPa), MoNbTaTiV (139 GPa), TiZrVNb (121 GPa), NbTaTiV (117 GPa), TaNbHfZrTi (104 GPa), TiZrHfNbCr (104 GPa), TiZrHfNbV (95 GPa) anc TiZrHfNb (89 GPa), and the maximum Young’s modulus (194 GPa) was lower than that of the (uncontaminated?) single phase solid solution RHEAs NbMoTaW (229 GPa), VnbMoTaW (205 GPa) and AlMoNbV (197 GPa) [ 86 ].…”

Strategies for Achieving Strength–Ductility Synergy in Face‐Centered Cubic High‐ and Medium‐Entropy Alloys

“…[142] In case of the precipitates possessing a large size or an incoherent relationship with the matrix, dislocations will choose to bypass them, which is the so-called Orowan bypass mechanism. [143] In theory, the contribution to strengthening from cutting (Δτ c ) and Orwan (Δτ O ) mechanisms can be expressed as, respectively [144] Δτ…”

“…[ 142 ] In case of the precipitates possessing a large size or an incoherent relationship with the matrix, dislocations will choose to bypass them, which is the so‐called Orowan bypass mechanism. [ 143 ] In theory, the contribution to strengthening from cutting (Δ τ c ) and Orwan (Δ τ O ) mechanisms can be expressed as, respectively [ 144 ] where F is the force implemented by obstacles, b the Burgers vector, 2 λ the average spacing between the precipitates, k c the material constant, G the shear modulus, r the radius of precipitates, and f V is the volume fraction of precipitates. At present, in the FCC HEAs/MEAs, the coherent precipitates mainly include the M 23 C 6 carbide, L1 2 phase with Ni 3 Al‐type ordered FCC structure, and D0 22 structured γ″ phase, while B 2 with NiAl‐type ordered BCC structure and some hard σ and μ intermetallic compounds are widely used as incoherent precipitates.…”

Modeling Radiation Damage in Materials Relevant for Exploration and Settlement on the Moon

“…The interest of researchers in MPEAs has been growing exponentially in recent years, as they exhibit a paradigm shift in alloy development. MPEAs indeed combine a set of outstanding properties, such as high strength, hardness, fracture toughness, corrosion resistance, strength retention at high temperature [226], good low-temperature performance [227], and recently discovered enhanced radiation resistance, superior to conventional alloys and pure metals [149,222,223,[228][229][230][231][232][233]. Moreover, MPEAs have great potential as 3D printing materials [234].…”