Effect of starting grain size on the evolution of microstructure and texture during thermo-mechanical processing of CoCrFeMnNi high entropy alloy

Sathiaraj, G. Dan; Bhattacharjee, P.P.

doi:10.1016/j.jallcom.2015.06.009

Cited by 72 publications

(16 citation statements)

References 46 publications

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“…3-8). Recrystallization of the fcc solid solution after annealing in the examined temperature range can be readily anticipated taking into account available information on alloys with similar compositions [20,38,42,[51][52][53]. However, some features of the carbide particles precipitation required additional consideration.…”

Section: Discussionmentioning

confidence: 99%

Recrystallized microstructures and mechanical properties of a C-containing CoCrFeNiMn-type high-entropy alloy

Klimova

Shaysultanov

Chernichenko

et al. 2019

Materials Science and Engineering: A

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The effect of cold rolling to 80% thickness reduction and annealing at 973-1373 K for 1 h on the microstructure and mechanical properties of a C-containing CoCrFeNiMn high-entropy alloy was studied. Cold rolling significantly strengthened the alloy to the yield strength of 1310 MPa. Annealing at 973 K or 1073 K resulted in incomplete recrystallization of an fcc matrix and M 23 C 6-type carbide precipitations aligned with highly elongated grains/subgrains. Complete recrystallization occurred during annealing at 1173 − 1373 K. The ordered arrangement of the carbides was not observed after annealing at 1273 K or 1373 K. The volume fraction of carbides decreased with increasing the annealing temperature that can be reasonably described by a Thermo-Calc prediction. The coarsening behavior of the microstructure constituents was studied during isothermal annealing at 1173 K for 1-50 h. It was found that the grain growth and the particle coarsening can be expressed by power law functions of annealing time with grain/particle size exponents of about 2 and 3, respectively. An increase in the annealing temperature from 973 K to 1373 K led to a gradual softening of the alloy; the yield strength decreased from 870 MPa to 320 MPa, whereas total elongation increased from 24% to 47%, respectively. Contributions of various strengthening mechanisms into the overall strength of the alloy were discussed.

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Section: Discussionmentioning

confidence: 99%

Recrystallized microstructures and mechanical properties of a C-containing CoCrFeNiMn-type high-entropy alloy

Klimova

Shaysultanov

Chernichenko

et al. 2019

Materials Science and Engineering: A

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“…It has also been suggested that the recrystallisation resistance observed in some HEAs provides evidence for their sluggish diffusion kinetics. 52,53,55,65,212,214 It is true that slow atomic diffusion does inhibit recrystallisation, but rates will also depend on other variables such as dislocation concentrations and distributions, prior grain size, and the presence of second phases or other inhomogeneities. 216 Hence, careful investigation is needed before recrystallisation kinetics are related to diffusion kinetics.…”

Section: Sluggish Diffusion Kineticsmentioning

confidence: 99%

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

Pickering

Jones

2016

International Materials Reviews

738

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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“…In the opinion of these authors, the distorted lattice of HEAs hindered atomic movement, resulting in sluggish transport properties and formation of precipitates of nanometric size due to reduced rates of nucleation and growth. This view was later adopted by several authors to explain their own results, as well as to explain other phenomena, such as, e.g., slow kinetic of oxidation or high creep resistance [16][17][18][19][20][21][22][23][24][25][26][27]. However, despite the frequent usage of the sluggish diffusion argument, the first direct diffusion studies, performed using the diffusion couple approach, were published by Tsai et al in 2013 [28], nine years after the first reports concerning the sluggish diffusion phenomenon.…”

Section: Studies Of Sluggish Diffusion Studies In High Entropy Alloysmentioning

confidence: 99%

State-of-the-Art Diffusion Studies in the High Entropy Alloys

Dąbrowa

Danielewski

2020

Metals

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The development of the high entropy alloys (HEAs) is amongst the most important topics in the field of materials science during the last two decades. The concept of multicomponent, near-equimolar systems has been already applied to the number of other systems, including oxides, carbides, diborides, silicides, and it can be expected that other groups of materials will follow. One of the main driving forces for the development of HEAs is the so-called “four core effects”: high entropy effects, severe lattice distortion, cocktail effect, and sluggish diffusion effect. Their existence and extent has been a subject of heated discussion. Probably the least studied of them is the sluggish diffusion effect, which is of the, especially, high importance from the point of view of the most possible applications of HEAs—as high-temperature materials. Its alleged existence carries a promise of obtaining materials with superior mechanical properties, higher creep resistance, and less susceptibility to high-temperature corrosion. In the current review, the state-of-the-art of diffusion studies in HEAs was presented, as well as the resulting conclusions concerning the existence of the sluggish diffusion effect. Based on the literature analysis, it can be stated that there is no experimental evidence, which would support the existence of the sluggish diffusion in HEAs on the level of tracer and self-diffusivities. Nevertheless, it can be pointed out that our current state of knowledge on the diffusion in HEAs is still far from complete; therefore, further directions of studies are proposed.

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Effect of starting grain size on the evolution of microstructure and texture during thermo-mechanical processing of CoCrFeMnNi high entropy alloy

Cited by 72 publications

References 46 publications

Recrystallized microstructures and mechanical properties of a C-containing CoCrFeNiMn-type high-entropy alloy

Recrystallized microstructures and mechanical properties of a C-containing CoCrFeNiMn-type high-entropy alloy

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

State-of-the-Art Diffusion Studies in the High Entropy Alloys

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