Design of high entropy alloys: A single-parameter thermodynamic rule

Ye, Y.F.; Wang, Q.; J, Lu; Liu, Chang; Yang, Yong

doi:10.1016/j.scriptamat.2015.03.023

Cited by 238 publications

(101 citation statements)

References 23 publications

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“…Many others have since followed this methodology, using the same parameters or others that provide measures of the same key effects. 163,204,252,253,255,258,[263][264][265][266]271 138,272 have used VEC alongside compositional considerations to predict σ formation in HEAs, while others have compared instances of ordered phase formation (including topologically close-packed phases, TCPs) against the average value of the d-orbital energy level 262,273 and Dx. 274 It has been suggested that Dx it is also an indicator of elemental segregation on casting.…”

Section: Phase Prediction and Alloy Selection In Heasmentioning

confidence: 99%

High-entropy alloys: a critical assessment of their founding principles and future prospects

Pickering

Jones

2016

International Materials Reviews

703

299

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High-entropy alloys (HEAs) are a relatively new class of materials that have gained considerable attention from the metallurgical research community over recent years. They are characterised by their unconventional compositions, in that they are not based around a single major component, but rather comprise multiple principal alloying elements. Four core effects have been proposed in HEAs: (1) the entropic stabilisation of solid solutions, (2) the severe distortion of their lattices, (3) sluggish diffusion kinetics and (4) that properties are derived from a cocktail effect. By assessing these claims on the basis of existing experimental evidence in the literature, as well as classical metallurgical understanding, it is concluded that the significance of these effects may not be as great as initially believed. The effect of entropic stabilisation does not appear to be overarching, insufficient evidence exists to establish the strain in the lattices of HEAs, and rapid precipitation observed in some HEAs suggests their diffusion kinetics are not necessarily anomalously slow in comparison to conventional alloys. The meaning and influence of the cocktail effect is also a matter for debate. Nevertheless, it is clear that HEAs represent a stimulating opportunity for the metallurgical research community. The complex nature of their compositions means that the discovery of alloys with unusual and attractive properties is inevitable. It is suggested that future activity regarding these alloys seeks to establish the nature of their physical metallurgy, and develop them for practical applications. Their use as structural materials is one of the most promising and exciting opportunities. To realise this ambition, methods to rapidly predict phase equilibria and select suitable HEA compositions are needed, and this constitutes a significant challenge. However, while this obstacle might be considerable, the rewards associated with its conquest are even more substantial. Similarly, the challenges associated with comprehending the behaviour of alloys with complex compositions are great, but the potential to enhance our fundamental metallurgical understanding is more remarkable. Consequently, HEAs represent one of the most stimulating and promising research fields in materials science at present.

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Section: Phase Prediction and Alloy Selection In Heasmentioning

confidence: 99%

High-entropy alloys: a critical assessment of their founding principles and future prospects

Pickering

Jones

2016

International Materials Reviews

703

299

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“…In order to predict the formation of solid solutions in HEAs, many phenomenological parameters based on thermodynamics and physics have been proposed [3,4,6,16,17,19,33]. In this study, several classic models were selected, and their main features are summarized as follows:…”

Section: Phase-formation Rules Of Heasmentioning

confidence: 99%

“…Recently, for the design of single-phase HEAs, Ye et al [19] proposed a single thermodynamic parameter, φ, taking into account the enthalpy of mixing and the excess entropy of mixing, which results from the dense atomic packing and atomic-size misfit. The single-parameter, φ, can be expressed as: .…”

Section: Phase-formation Rules Of Heasmentioning

confidence: 99%

“…The trial-and-error approach that has been used for traditional alloys design is costly and time-consuming for the discovery of new HEAs because of the vast compositional space that they occupy. As a consequence, efforts have been made to study HEA phase-formation rules to accelerate the discovery process [4,[16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Taking advantage of the phase-formation rules, the constitutive phases in HEAs can be controlled and adjusted to improve mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

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Design of Light-Weight High-Entropy Alloys

Feng

Gao

Lee

et al. 2016

Entropy

197

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High-entropy alloys (HEAs) are a new class of solid-solution alloys that have attracted worldwide attention for their outstanding properties. Owing to the demand from transportation and defense industries, light-weight HEAs have also garnered widespread interest from scientists for use as potential structural materials. Great efforts have been made to study the phase-formation rules of HEAs to accelerate and refine the discovery process. In this paper, many proposed solid-solution phase-formation rules are assessed, based on a series of known and newly-designed light-weight HEAs. The results indicate that these empirical rules work for most compositions but also fail for several alloys. Light-weight HEAs often involve the additions of Al and/or Ti in great amounts, resulting in large negative enthalpies for forming solid-solution phases and/or intermetallic compounds. Accordingly, these empirical rules need to be modified with the new experimental data. In contrast, CALPHAD (acronym of the calculation of phase diagrams) method is demonstrated to be an effective approach to predict the phase formation in HEAs as a function of composition and temperature. Future perspectives on the design of light-weight HEAs are discussed in light of CALPHAD modeling and physical metallurgy principles.

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“…In such condition, besides just theoretical modeling [35,38,[52][53][54], computational approaches, such as density functional theory (DFT) calculations [55] and ab initio molecular dynamics (AIMD) [56] simulations, can also be used to study phase formation in HEAs. Due to the significant cost and computational time required based on the current technology and among other limitations [17], these approaches are not feasible for designing of HEAs.…”

Section: Theoretical Aspects and Designing Of A Lwheamentioning

confidence: 99%

An Insight into Evolution of Light Weight High Entropy Alloys: A Review

Kumar

Gupta

2016

Metals

135

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High Entropy Alloys (HEAs) are the most recently developed new class of materials, which are known for their unique structural properties. Lightweight materials are currently in excessive demand for transportation and energy saving applications. In this review, efforts have been made to summarize the work done towards the development of HEAs targeting lightweight applications. Some new synthesis techniques are suggested for the fabrication of lightweight HEAs (LWHEAs). The concept of porous structure fabrication, microwave sintering of green compact, casting by disintegration melt deposition and advanced manufacturing using additive manufacturing are discussed as future directions of LWHEAs synthesis. LWHEAs for potential biomedical applications have also been addressed.

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Design of high entropy alloys: A single-parameter thermodynamic rule

Cited by 238 publications

References 23 publications

High-entropy alloys: a critical assessment of their founding principles and future prospects

High-entropy alloys: a critical assessment of their founding principles and future prospects

Design of Light-Weight High-Entropy Alloys

An Insight into Evolution of Light Weight High Entropy Alloys: A Review

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