Experiments and Model for Serration Statistics in Low-Entropy, Medium-Entropy and High-Entropy Alloys

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.

show abstract

“…For instance, a number of studies have observed serrations in the stress-strain curves of HEAs, 42,319,320 see Fig. 11.…”

Section: Improved Understandingmentioning

confidence: 99%

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

Pickering

Jones

2016

International Materials Reviews

700

299

View full text Add to dashboard Cite

show abstract

“…As a result, the stability region of the high-entropy disordered phase becomes larger when additional neutral strategies are introduced into an elementary coordination game. A similar entropy-based stabilization is characteristic of high-entropy alloys [49][50][51], a promising family of materials for several technical purposes. If decoupling of independent game components holds at the mean-field level, then the above-described results should give us an idea about what happens in games made up of an Ising and an (n − 2)-strategy Potts subgame, just like the one in Equation (2).…”

Section: Resultsmentioning

confidence: 99%

Entropy Affects the Competition of Ordered Phases

Király

Szabó

2018

Entropy

View full text Add to dashboard Cite

Abstract:The effect of entropy at low noises is investigated in five-strategy logit-rule-driven spatial evolutionary potential games exhibiting two-fold or three-fold degenerate ground states. The non-zero elements of the payoff matrix define two subsystems which are equivalent to an Ising or a three-state Potts model depending on whether the players are constrained to use only the first two or the last three strategies. Due to the equivalence of these models to spin systems, we can use the concepts and methods of statistical physics when studying the phase transitions. We argue that the greater entropy content of the Ising phase plays an important role in its stabilization when the magnitude of the Potts component is equal to or slightly greater than the strength of the Ising component. If the noise is increased in these systems, then the presence of the higher entropy state can cause a kind of social dilemma in which the players' average income is reduced in the stable Ising phase following a first-order phase transition.

show abstract

“…In addition, it is interesting that the serrated fluctuation behavior is presented on the stress-strain curve after a uniaxial compression test. This serrated flow behavior is widely investigated both in HEAs [15,16] and amorphous alloys [17]. In the crystalline alloys, the intermittent yielding exhibits temporal fluctuations during plastic deformation on the stress-strain curves [18], which is called the Portevin-Le Chatelier (PLC) effect [19].…”

Section: Introductionmentioning

confidence: 99%

Serration Behavior in Pd77.5Cu6Si16.5 Alloy

Zhong¹,

Li²,

Yuan³

et al. 2016

Metals

View full text Add to dashboard Cite

Abstract:The strain-rate-dependent plasticity under uniaxial compression at the strain rates of 2 × 10 −3 , 2 × 10 −4 and 2 × 10 −5 s −1 in a Pd 77.5 Cu 6 Si 16.5 alloy is investigated. At different strain rates, the serration events exhibit different amplitudes and time scales. The intersection effects take place obviously, and the loading time is much longer than the relaxation time in the serration event at three strain rates. However, the time intervals between two neighboring serrations lack any time scale, and the elastic energy density displays a power-law distribution at the strain rate of 2 × 10 −3 s −1 , which means that the self-organized critical (SOC) behavior emerges with increasing strain rates.

show abstract

Experiments and Model for Serration Statistics in Low-Entropy, Medium-Entropy and High-Entropy Alloys

Cited by 117 publications

References 47 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

Entropy Affects the Competition of Ordered Phases

Serration Behavior in Pd77.5Cu6Si16.5 Alloy

Contact Info

Product

Resources

About