Mechanical behavior of high-entropy alloys: A review

Shang, Yuanyuan; Brechtl, Jamieson; Psitidda, Claudio; Liaw, Peter K.

doi:10.48550/arxiv.2102.09055

Cited by 2 publications

(2 citation statements)

References 315 publications

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“…Figure 9 plots the w sb and h min estimates for different glasses against the corresponding atomic size mismatch parameter δ a = √ var(a i )/ a i . The latter is defined as the normalized standard deviation associated with radius a i of atom i = 1...N. In the context of high-entropy alloys, δ a is believed to strongly control the degree of local lattice distortions [40]. We generalize this concept to glassy alloys where the size mismatch parameter may be thought as a structural proxy controlling the degree of quenched disorder.…”

Section: B Shear Band Characterizationmentioning

confidence: 99%

Shear banding instability in multicomponent metallic glasses: Interplay of composition and short-range order

et al. 2022

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The shear-banding instability in quasistatically driven bulk metallic glasses emerges from collective dynamics, mediated by shear transformation zones and associated nonlocal elastic interactions. It is also phenomenologically known that sharp structural features of shear bands are typically correlated to the sharpness of the plastic yielding transition, being predominant in commonly studied alloys composed of multiple different elements, that have very different atomic radii. However, in the opposite limit where elements' radii are relatively similar, plastic yielding of bulk metallic glasses is highly dependent on compositional and ordering features. In particular, a known mechanism at play involves the formation of short-range order dominated by icosahedrabased clusters. Here, we report on atomistic simulations of multicomponent metallic glasses with different chemical compositions showing that the degree of strain localization is largely controlled by the interplay between composition-driven icosahedra-ordering and collectively-driven shear transformation zones. By altering compositions, strain localization ranges from diffuse homogenized patterns to singular crack-like features. We quantify the dynamical yielding transition by measuring the atoms' susceptibility to plastic rearrangements, strongly correlated to the local atomic structure. We find that the abundance of short-range ordering of icosahedra within rearranging zones increases glassy materials' capacity to delocalize strain. This could be understood on the basis of structural heterogeneities that are enhanced by the presence of local order. The kind of plastic yielding can be often qualitatively inferred by the commonly used compositional descriptor that characterizes element associations, the misfit parameter δ a , and also by uncommon ones, such as shear-band width and shear-band dynamics' correlation parameters.

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Section: B Shear Band Characterizationmentioning

confidence: 99%

Shear banding instability in multicomponent metallic glasses: Interplay of composition and short-range order

et al. 2022

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“…The choices of the studied materials are motivated by prior studies that provided benchmarks for traditional depinning behavior (Fe 0.7 Ni 0.11 Cr 0.19 [13], FeNi [14]), and also by motivating experimental findings on equiatomic multicomponent alloys (CrCoNi, CrMnCoNi, CrFeCoNi, CrMnFeCoNi, Fe 0.4 Mn 0.27 Ni 0.26 Co 0.05 Cr 0.02 ) that point towards exceptional strength [17][18][19][20][21]. Equiatomic fcc HEAs with low stacking fault energy showed an excellent balance between strength and ductility, particularly at cryogenic temperatures [3,4].…”

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confidence: 99%

Edge dislocations in multi-component solid solution alloys: Beyond traditional elastic depinning

Esfandiarpour¹,

Papanikolaou²,

Alava³

2021

Preprint

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High-entropy alloys (HEA) form solid solutions with large chemical disorder and excellent mechanical properties. We investigate the origin of HEA strengthening in face-centered cubic (FCC) singlephase HEAs through molecular dynamics simulations of dislocations, in particular, the equiatomic CrCoNi, CrMnCoNi, CrFeCoNi, CrMnFeCoNi, FeNi, and also, Fe0.4Mn0.27Ni0.26Co0.05Cr0.02, Fe0.7Ni0.11Cr0.19. The dislocation correlation length ξ, roughness amplitude Ra, and stacking fault widths WSF are tracked as a function of stress. All alloys are characterized by a well defined depinning stress (σc) and we find a novel regime where exceptional strength is observed, and a fortuitous combination takes place, of small stacking fault widths and large dislocation roughness Ra. Thus the depinning of two partials seems analogous to unconventional domain wall depinning in disordered magnetic thin films. This novel regime is identified in specific compositions commonly associated with exceptional mechanical properties (CrCoNi, CrMnCoNi, CrFeCoNi, and CrMnFeCoNi). Yield stress from analytical solute-strengthening models underestimates largely the results in these cases. A possible strategy for increasing strength in multi-component single-phase alloys is the combined design of stacking fault width and element-based chemical disorder.

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Mechanical behavior of high-entropy alloys: A review

Cited by 2 publications

References 315 publications

Shear banding instability in multicomponent metallic glasses: Interplay of composition and short-range order

Shear banding instability in multicomponent metallic glasses: Interplay of composition and short-range order

Edge dislocations in multi-component solid solution alloys: Beyond traditional elastic depinning

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