Twenty years of the CoCrFeNiMn high-entropy alloy: achieving exceptional mechanical properties through microstructure engineering

Shahmir, Hamed; Mehranpour, Mohammad Sajad; Shams, Seyed Amir Arsalan; Langdon, Terence G.

doi:10.1016/j.jmrt.2023.01.181

Cited by 66 publications

(12 citation statements)

References 284 publications

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“…The of complex heterogeneous structures affects deformation mechanisms and changes strain hardenability during straining in a way that leads to the improvement of mechanical properties. Basically, the CoCrFeNiMn alloy with a simple fcc crystal structure has great potential for easy deformation via dislocation slip due to the large number of slip systems, together with deformation twinning as a result of its low SFE [18]. These two processes are known as the controlling deformation mechanisms in CoCrFeNiMn HEAs with a homogeneous grain structure.…”

Section: Deformation Mechanisms In the Heterogeneous Structurementioning

confidence: 99%

“…Thermomechanical treatment, including cold rolling, to activate strain hardening followed by post-deformation annealing to obtain a favorable microstructure is a process that is easy to develop for industrial applications. However, the degree of plastic deformation, ranging from small to heavy/severe plastic deformation, the processing temperature (cryo-to warm rolling), annealing temperature (500-1000 • C) and time (a few to a hundred minutes) are control parameters for microstructure engineering, used to obtain desirable mechanical properties [17,18]. The alloy strength increased slightly after applying the thermomechanical procedure due to the formation of fine or ultrafine grains.…”

Section: Introductionmentioning

confidence: 99%

“…In this case, it was reported earlier in different investigations that the formation of brittle sigma precipitates deteriorates the ductility [19][20][21][22]. Most investigations performed earlier were focused on full recrystallization and tailoring the microstructure through grain refinement, together with appropriate precipitates, to achieve optimal mechanical properties [18][19][20][21][22][23]. Severe or heavy deformation may promote precipitation due to the existence of a large number of grain boundaries and dislocations as fast diffusion pathways and preferential nucleation sites during short-term annealing at intermediate temperatures [21].…”

Section: Introductionmentioning

confidence: 99%

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Hetero-Deformation Induced Hardening in a CoCrFeNiMn High-Entropy Alloy

et al. 2023

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One of the most important issues in materials science is to overcome the strength–ductility trade-off in engineering alloys. The formation of heterogeneous and complex microstructures is a useful approach to achieving this purpose. In this investigation, a CoCrFeNiMn high-entropy alloy was processed via cold rolling followed by post-deformation annealing over a temperature range of 650–750 °C, which led to a wide range of grain sizes. Annealing at 650 °C led to the formation of a heterogeneous structure containing recrystallized areas with ultrafine and fine grains and non-recrystallized areas with an average size of ~75 μm. The processed material showed strength–ductility synergy with very high strengths of over ~1 GPa and uniform elongations of over 12%. Different deformation mechanisms such as dislocation slip, deformation twinning and hetero-deformation-induced hardening were responsible for achieving this mechanical property. Increasing the annealing temperature up to 700 °C facilitated the acquisition of bimodal grain size distributions of ~1.5 and ~6 μm, and the heterogeneous structure was eliminated via annealing at higher temperatures, which led to a significant decrease in strength.

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Section: Deformation Mechanisms In the Heterogeneous Structurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hetero-Deformation Induced Hardening in a CoCrFeNiMn High-Entropy Alloy

et al. 2023

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“…The first report was a superplastic elongation of 1240% in an AlCoCrCuFeNi alloy processed by multiaxial forging [36] and there were later reports of superplasticity in a CoCrFeNiMn HEA [37] and an elongation of up to 2000% in an Al9(CoCrFeNiMn)91 (at.%) alloy [38]. A comprehensive review is now available summarizing the properties of the traditional CoCrFeNiMn HEA [39]. More recently, results have become available showing the occurrence of superplastic elongations in multi-principal element alloys (MPEAs) [40,41].…”

Section: Recent Developments In the Superplasticity Of Metalsmentioning

confidence: 99%

New developments in the processing of metallic alloys for achieving exceptional superplastic properties

Wang

2023

Superplasticity in Advanced Materials

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Abstract. The process of superplasticity has a long history dating back to the early experiments of Pearson conducted in the U.K. in 1934. Since that time, superplasticity has become of increasing importance because of the recognition that superplastic forming provides a simple procedure for the processing of complex and curved parts for use in a wide range of industrial applications. The fundamental requirement for superplastic flow is a small grain size typically smaller than ~10 µm. These fine grains were achieved traditionally through the use of appropriate thermo-mechanical processing which provided a procedure for developing microstructures having grain sizes of the order of a few micrometers. Over the last two decades the processing procedures have been further developed through the use of techniques based on the application of severe plastic deformation (SPD) where it is possible to achieve ultrafine-grained materials with grains sizes in the submicrometer or even the nanometer range. Early SPD experiments were conducted using the processes of equal-channel angular pressing or high-pressure torsion but more recently a new and improved technique was developed which is known as tube high-pressure shearing (t-HPS). Experiments show that t-HPS provides a capability of producing exceptional superplastic elongations with, for example, an elongation of ~2320% in a Bi-Sn alloy when tested at a strain rate of 10-4 s-1 at room temperature. This report examines these recent developments with an emphasis on the potential for improving the superplastic capabilities of metallic alloys.

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“…[11][12][13] In fact, the existence of such a dilemma in HEAs is not surprising. This is because similar to traditional alloys, some strengthening mechanisms also apply for HEAs, such as second-phase strengthening, dislocation strengthening, and so on, [14] while they sometimes may cause the deterioration of corrosion resistance. For instance, the grain refinement can provide superior strength according to the Hall-Petch relation, but high-density grain boundary accelerates the segregation of alloying elements due to higher interfacial energy, which is susceptible to the galvanic corrosion.…”

Section: Introductionmentioning

confidence: 99%

Effect of Al Content on Microstructure, Mechanical, and Corrosion Properties of (Fe₃₃Cr₃₆Ni₁₅Co₁₅Ti₁)_100−xAl_x High‐Entropy Alloys

Zheng,

Lu,

Han

et al. 2023

Adv Eng Mater

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(Fe33Cr36Ni15Co15Ti1)100−x Al x (x=0, 3, 5, 6, 7, 8) high entropy alloys (HEAs) were prepared by arc‐melting. The influence of Al element addition on the microstructure, mechanical properties, and anti‐corrosion in 3.5 wt.% NaCl aqueous solution was systematically investigated. The microstructure analysis indicated that HEAs possessed varying phases from FCC+Sigma to FCC+BCC and then FCC+BCC+Sigma, the last to BCC+Sigma with the increase of Al content. The compressive results suggested that the Al addition exhibited a significant elevation in strength. Particularly, Al7 alloy performed a superior strength and plasticity, which presented a yield strength of 1315.3 MPa and a compressive strain over 50%. Order strengthening and coherent strengthening of nanosized phase were regarded as main strengthening effects. In addition, Al element was harmful for the corrosion resistance (Epit and Icorr) of (Fe33Cr36Ni15Co15Ti1)100−x Al x HEAs system, which was ascribed to the weakened passive film stability. It was also noted that pits tended to be initiated in relatively Cr‐depleted phases (FCC or B2 phase) due to the inhomogeneous elemental distribution induced galvanic corrosion. In spite of this, all HEAs exhibit superior corrosion resistance than that of 304SS. This work provides a beneficial guidance for alloy design simultaneously regarding strength, ductility, and corrosion.This article is protected by copyright. All rights reserved.

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Twenty years of the CoCrFeNiMn high-entropy alloy: achieving exceptional mechanical properties through microstructure engineering

Cited by 66 publications

References 284 publications

Hetero-Deformation Induced Hardening in a CoCrFeNiMn High-Entropy Alloy

Hetero-Deformation Induced Hardening in a CoCrFeNiMn High-Entropy Alloy

New developments in the processing of metallic alloys for achieving exceptional superplastic properties

Effect of Al Content on Microstructure, Mechanical, and Corrosion Properties of (Fe₃₃Cr₃₆Ni₁₅Co₁₅Ti₁)_100−xAl_x High‐Entropy Alloys

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Twenty years of the CoCrFeNiMn high-entropy alloy: achieving exceptional mechanical properties through microstructure engineering

Cited by 66 publications

References 284 publications

Hetero-Deformation Induced Hardening in a CoCrFeNiMn High-Entropy Alloy

Hetero-Deformation Induced Hardening in a CoCrFeNiMn High-Entropy Alloy

New developments in the processing of metallic alloys for achieving exceptional superplastic properties

Effect of Al Content on Microstructure, Mechanical, and Corrosion Properties of (Fe33Cr36Ni15Co15Ti1)100−xAlx High‐Entropy Alloys

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Product

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About

Effect of Al Content on Microstructure, Mechanical, and Corrosion Properties of (Fe₃₃Cr₃₆Ni₁₅Co₁₅Ti₁)_100−xAl_x High‐Entropy Alloys