High-temperature deformation mechanisms and processing maps of equiatomic CoCrFeMnNi high-entropy alloy

Jeong, Heon; Park, H.K.; Park, K.; Na, Tae‐Wook; Kim, Woo Jin

doi:10.1016/j.msea.2019.04.057

Cited by 90 publications

(23 citation statements)

References 37 publications

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“…where β i = (e −u − e −v 0 ) / (e −u + e −v 0 + r 0 ) , i even (e −v 1 − e −u ) / (e −u + e −v 1 + r 1 ) , i odd (32) and represent the ceiling and floor functions, respectively. r 1 is the sum of all transition rates from site 1 not explicitly given, while r 0 is the same for site 0.…”

Section: S3 Higher-order Correlation Factorsmentioning

confidence: 99%

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Vacancy Diffusion in Multi-Principal Element Alloys: The Role of Chemical Disorder in the Ordered Lattice

Thomas

Patala

2020

SSRN Journal

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Many of the purported virtues of Multi-Principal Element Alloys (MPEAs), such as corrosion, high-temperature oxidation and irradiation resistance, are highly sensitive to vacancy diffusivity. Similarly, solute interdiffusion is governed by vacancy diffusion -it is often unclear whether MPEAs are truly stable, or effectively stabilized by slow interdiffusion. The considerable composition space afforded to these alloys makes optimizing for desired properties a daunting task; theoretical and computational tools are necessary to guide alloy development. For diffusion, such tools depend on both a knowledge of the vacancy migration barriers within a given alloy and an understanding of how these barriers influence vacancy diffusivity. We present a generalized theory of vacancy diffusion in rugged energy landscapes, paired with Kinetic Monte Carlo simulations of MPEA vacancy diffusion. The barrier energy statistics are informed by nudged elastic band calculations in the equiatomic CoNiCrFeMn alloy. Theory and simulations show that vacancy diffusion in solid-solution MPEAs is not necessarily sluggish, but can potentially be tuned, and that trap models are an insufficient explanation for sluggish diffusion in the CoNiCrFeMn MPEA. These results also show that any model that endeavors to faithfully represent diffusion-related phenomena must account for the full nature of the energy landscape, not just the migration barriers.

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Section: S3 Higher-order Correlation Factorsmentioning

confidence: 99%

“…Under extreme environments, the diffusivity of point-defects (vacancies) governs the performance and the microstructural stability of MPEAs. Therefore, determination of the kinetics of phase transformations and operating temperatures for these alloys demands a thorough understanding of the transport coefficients [32].…”

Section: Introductionmentioning

confidence: 99%

Vacancy Diffusion in Multi-Principal Element Alloys: The Role of Chemical Disorder in the Ordered Lattice

Thomas

Patala

2020

SSRN Journal

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“…Eleti et al [34], on the other hand, have reported high-temperature deformation characteristics of a hot forged (1023 K) CoCrFeMnNi HEA compressed at different temperatures (1073 K, 1173 K and 1273 K) and strain rates (10 −3 s −1 , 10 −2 s −1 and 1 s −1 ). While Jeong et al [33] determined the activation energy of deformation (Q) to be about 312 kJ/mol for CoCrFeMnNi HEA, the corresponding calculations by Eleti et al [34] based on a narrow temperature range gave a higher value of 350kJ/mol. Stepanov et al [35] and Eleti et al [34] have reported an account of the grain refinement due to the occurrence of dynamic recrystallization (DRX) during hot deformation of CoCrFeMnNi alloy.…”

Section: Introductionmentioning

confidence: 98%

“…The hot deformation studies illustrating the constitutive flow behaviour of CoCrFeMnNi HEA are limited. Jeong et al [33] have reported high-temperature hot deformation behaviour of a cast and homogenized CoCrFeMnNi HEA (average grain size 419 µm) in the temperature and strain rate regimes of 1023-1323 K and 10 −3 s −1 to 10 s −1 , respectively, and developed processing maps. Eleti et al [34], on the other hand, have reported high-temperature deformation characteristics of a hot forged (1023 K) CoCrFeMnNi HEA compressed at different temperatures (1073 K, 1173 K and 1273 K) and strain rates (10 −3 s −1 , 10 −2 s −1 and 1 s −1 ).…”

Section: Introductionmentioning

confidence: 99%

“…These hyperbolic sinusoidal Arrhenius-type equations are found to predict the flow stress accurately over a wide range of hot deformation conditions [42]. Eleti et al [34] and Jeong et al [33] had used the hyperbolic sinusoidal Arrhenius-type expressions to obtain the constitutive equations of CoCrFeMnNi HEA. However, the derived constitutive equations were restricted to only a select true strain (0.9 [34] and 0.6 [33]).…”

Section: Introductionmentioning

confidence: 99%

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Constitutive modelling of hot deformation behaviour of a CoCrFeMnNi high-entropy alloy

Patnamsetty

Saastamoinen

Somani

et al. 2020

Science and Technology of Advanced Materials

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Models describing the constitutive flow behaviour of a metallic material are desired for appropriate process design and realization of defect-free components. In this study, constitutive equations based on the hyperbolic-sinusoidal Arrhenius-type model have been developed to define the hot deformation characteristics of a CoCrFeMnNi high-entropy alloy. The experimental true stress-true strain data were generated over a wide temperature (1023-1423 K) and strain rates (10 −3-10 s −1) ranges. The impact of strain rate and temperature on deformation behaviour was further characterized through a temperature compensated strain rate parameter, i.e. Zener-Hollomon parameter. Additionally, a mathematical relation was employed to express the influence of various material constants on true-strain ranging from 0.2 to 0.75. Typical third order polynomial relations were found to be appropriate to fit the true-strain dependency of these material constants. The accuracy of the developed constitutive equations was evaluated by using the average absolute relative error (AARE) and correlation coefficient (R); the obtained values were 7.63% and 0.9858, respectively, suggesting reasonable predictions. These results demonstrate that the developed constitutive equations can predict the flow stress behaviour of the alloy with a good accuracy over a wide range of temperature and strain rate conditions and for large strains.

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Mechanical Properties and Mechanisms of Deformation of High Entropy Alloys

Громов

Коновалов

Ivanov

et al. 2021

Advanced Structured Materials

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High-temperature deformation mechanisms and processing maps of equiatomic CoCrFeMnNi high-entropy alloy

Cited by 90 publications

References 37 publications

Vacancy Diffusion in Multi-Principal Element Alloys: The Role of Chemical Disorder in the Ordered Lattice

Vacancy Diffusion in Multi-Principal Element Alloys: The Role of Chemical Disorder in the Ordered Lattice

Constitutive modelling of hot deformation behaviour of a CoCrFeMnNi high-entropy alloy

Mechanical Properties and Mechanisms of Deformation of High Entropy Alloys

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