The microstructure and mechanical behavior of modern high temperature alloys

Samaei, Arash; Mirsayar, MirMilad; Aliha, M.R.M.

doi:10.5267/j.esm.2015.1.001

Cited by 21 publications

(6 citation statements)

References 76 publications

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“…It also could be found that at a higher temperature, the curve showed more violent fluctuations, which was caused by the vibration of atoms and fading of the bonding strength between atoms. This phenomenon was also found in the experiments [13,40]. The nanoindentation load-displacement curves of HEAs with different Cu concentrations were shown in Figure 3(b).…”

Section: Resultssupporting

confidence: 81%

Nanoindentation into FeCoNiCrCu high-entropy alloy: An atomistic study

Han

Song

et al. 2021

Materials Science and Technology

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The mechanical behaviours of FeCoNiCrCu high entropy alloys (HEAs) were studied via large-scale molecular dynamics (MD) simulations. A rigid indenter was applied in the indentation to investigate the microstructural evolution and mechanical properties of HEAs in terms of indentation force, Young's modulus, dislocation behaviours, and shear strain distributions. Effects of Cu precipitation on the mechanical properties of HEAs were discussed. The modulus calculated from simulations were inconsistent with experiments. The precipitation of Cu will increase the elastic modulus of the matrix, while the solution of Cu into the matrix can increase the work strengthening rate. The coherent interface of Cu precipitation can contribute to a high work strengthening rate, while the incoherent interface will lead to a lower deformation resistance.

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Section: Resultssupporting

confidence: 81%

Nanoindentation into FeCoNiCrCu high-entropy alloy: An atomistic study

Han

Song

et al. 2021

Materials Science and Technology

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“…1, and a number of reviews of the HEA literature have been made over the past 5 years. 5,6,8,[10][11][12][13] These have been in the form of comprehensive and detailed summaries, such as the review by Zhang et al, 14 as well as shorter critical assessments, such as the recent work of Miracle. 15 However, none of these have critically assessed the evidence for the four core effects described above -this is one, and the most important, of the three key aims of this review, and is tackled to begin with.…”

Section: Introductionmentioning

confidence: 99%

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

Pickering

Jones

2016

International Materials Reviews

742

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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“…Thermoelectric properties can be tuned with respect to valence electron concentration (VEC) and a dimensionless thermoelectric figure of merit ( ZT ) of 0.012 at 505 °C was reached for Al 2 CoCrFeNi. The phase evolution of HEAs has been extensively studied both ex situ and in situ [ 7 , 8 , 9 , 10 , 11 ].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Scandium Ternary Intergrain Precipitates in Al-Containing High-Entropy Alloys

Riva

Mehraban

Lavery

et al. 2018

Entropy

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Abstract:We investigate the effect of alloying with scandium on microstructure, high-temperature phase stability, electron transport, and mechanical properties of the Al 2 CoCrFeNi, Al 0.5 CoCrCuFeNi, and AlCoCrCu 0.5 FeNi high-entropy alloys. Out of the three model alloys, Al 2 CoCrFeNi adopts a disordered CsCl structure type. Both of the six-component alloys contain a mixture of body-centered cubic (bcc) and face centered cubic (fcc) phases. The comparison between in situ high-temperature powder diffraction data and ex situ data from heat-treated samples highlights the presence of a reversible bcc to fcc transition. The precipitation of a MgZn 2 -type intermetallic phase along grain boundaries following scandium addition affects all systems differently, but especially enhances the properties of Al 2 CoCrFeNi. It causes grain refinement; hardness and electrical conductivity increases (up to 20% and 14% respectively) and affects the CsCl-type → fcc equilibrium by moving the transformation to sensibly higher temperatures. The maximum dimensionless thermoelectric figure of merit (ZT) of 0.014 is reached for Al 2 CoCrFeNi alloyed with 0.3 wt.% Sc at 650 • C.

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The microstructure and mechanical behavior of modern high temperature alloys

Cited by 21 publications

References 76 publications

Nanoindentation into FeCoNiCrCu high-entropy alloy: An atomistic study

Nanoindentation into FeCoNiCrCu high-entropy alloy: An atomistic study

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

The Effect of Scandium Ternary Intergrain Precipitates in Al-Containing High-Entropy Alloys

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