Comparison of cryogenic deformation of the concentrated solid solutions CoCrFeMnNi, CoCrNi and CoNi

Tirunilai, Aditya Srinivasan; Hanemann, Theresa; Reinhart, C.; Tschan, V.; Weiss, Klaus-Peter; Laplanche, Guillaume; Freudenberger, J.; Heilmaier, Martin; Kauffmann, Alexander

doi:10.1016/j.msea.2020.139290

Cited by 48 publications

(27 citation statements)

References 46 publications

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“…4a and Fig. 5a), covering an area fraction of about 35%, due to its low stacking fault energy (SFE) [6][7][8]25]. The average grain size was determined to be  6.4 µm via EBSD.…”

Section: Before Cyclic Strainingmentioning

confidence: 99%

“…For Al0.3CoCrFeNi HEA, Yasuda et al [60] showed that the solute atmosphere of Al atoms around moving dislocations or stacking faults is closely related to the DSA. For CoCrFeMnNi, DSA related serrations are reported to have occurred at both cryogenic temperature (4.2 K/8 K) [7,8] and elevated temperature range (300 °C to 620 °C) [58,59]. Wu et al [58] and Carroll et al [59] performed systematic studies using different compositional subsets of CoCrFeMnNi HEA.…”

Section: Serrated Flowmentioning

confidence: 99%

“…This alloy design concept provides many options to vary alloy chemistry, and hence, to improve the strength and ductility trade-off [1][2][3][4]. At room temperature (RT) for example, the equiatomic CoCrFeMnNi HEA, a faced-centered cubic (FCC) solid solution, first reported by Cantor et al [2], exhibits an ultimate tensile strength of ~ 700 MPa, ductility of ~50%, fracture toughness values exceeding 200 MPa√m, as well as high corrosion and oxidation resistance [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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High-temperature low cycle fatigue behavior of an equiatomic CoCrFeMnNi high-entropy alloy

Chauhan

Litvinov

et al. 2020

Materials Science and Engineering: A

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In the present work, low cycle fatigue (LCF) behavior of an equiatomic CoCrFeMnNi high entropy alloy (HEA) is correlated to the microstructural evolution at 550 °C. The fully reversed strain-controlled fatigue tests were conducted in air under strain amplitudes ranging from 0.2 to 0.8%. The measured cyclic stress response showed three distinct stages which include initial cyclic hardening followed by a quasi-stable cyclic response until failure. The rate and amount of cyclic hardening increased with the increase in strain amplitude. In comparison to common austenitic stainless steels, CoCrFeMnNi HEA shows comparable strength and improved LCF lifetimes at similar testing conditions. Electron-microscopy investigations after failure reveal no noticeable change in grain size, texture and annealing twins density. Initial cyclic hardening is attributed to dislocation multiplication and dislocation-dislocation as well as dislocationsolute atom interaction. The quasi-stable cyclic response is associated with the equilibrium between dislocation multiplication and annihilation, which also leads to the formation of heterogeneous dislocation structures such as ill-defined walls and cells, particularly at higher strain amplitudes. Besides this, the material exhibits serrated plastic-flow due to interactions between mobile dislocations and diffusing solute 2 atoms (such as Cr, Mn and Ni). Lastly, segregation in the form of Cr-and NiMn-enriched phases were observed near grain boundaries, which appears to have a detrimental effect on the fatigue life.

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“…4a and Fig. 5a), covering an area fraction of about 35%, due to its low stacking fault energy (SFE) [6][7][8]25]. The average grain size was determined to be  6.4 µm via EBSD.…”

Section: Before Cyclic Strainingmentioning

confidence: 99%

Section: Serrated Flowmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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High-temperature low cycle fatigue behavior of an equiatomic CoCrFeMnNi high-entropy alloy

Chauhan

Litvinov

et al. 2020

Materials Science and Engineering: A

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“…Among various HEAs, CoCrFeMnNi, also known as the Cantor alloy [9], has served as a model face centered cubic (FCC) alloy [10,11,12,13,14]. This alloy is known to exhibit interesting mechanical behavior at cryogenic temperatures, including strong work-hardening with decreasing temperature [15], activation of deformation twinning at cryogenic temperatures [10] and intense serrated plastic deformation at very low temperatures [16,17]. The current article focusses on the last of these issues.…”

Section: Introductionmentioning

confidence: 99%

“…detailed discussion of deformation behavior and microstructural evolution can be found in Refs. [15,16].…”

Section: Introductionmentioning

confidence: 99%

Dislocation-based serrated plastic flow of high entropy alloys at cryogenic temperatures

et al. 2020

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Serrated plastic deformation at temperatures close to 0 K has been previously reported in some metals and alloys, and is associated with two possible origins: (i) thermomechanical instability or (ii) mechanical instability. While some recent results indicate that serrations are a mechanical dislocation-based phenomenon, a comprehensive model does not exist. CoCrFeMnNi, an expectedly ideal candidate, exhibits severe serrated plastic deformation with large stress drops in excess of 100 MPa. Furthermore, it also shows cryogenic serrated plastic deformation at a higher temperature (35 K) than previously reported for any other alloy. The exacerbated nature of serrated plastic deformation in CoCrFeMnNi led to the following inferences: (i) temperature and dislocation density are indisputable controlling parameters for cryogenic serrated plastic deformation and they cannot supersede each another; (ii) a phenomenological model is elucidated based on the increasing difficulty for cross-slip with decreasing temperature, leading to sudden massive dislocation proliferation event;(iii) the model establishes a gradual transition from completely non-serrated to completely serrated deformation, mediated by cross-slip, as opposed to the conventional model which proposed a discrete transition; (iv) solute dislocation interaction and associated Stacking Fault Energy (SFE) during deformation plays a key role in controlling dislocation constriction and cross-slip and correspondingly serrated plastic deformation; (v) the need/direct influence of deformation twinning, transformation induced plasticity and especially thermomechanical factors on serrated plastic deformation is invalidated. Some of these points were further clarified through comparisons with CoCrNi and CoNi, also presented in the present article.

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Effect of V Content on the Microstructure and Mechanical Properties of High‐Pressure Torsion Nanostructured CoCrFeMnNiV_x High‐Entropy Alloys

Tabachnikova,

Smirnov,

Shapovalov

et al. 2024

Adv Eng Mater

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The paper presents investigations of microstructure and low‐temperature mechanical properties of nanostructured alloys CoCrFeMnNiVx (x = 0.15 – 0.75), processed by high‐pressure torsion (HPT) at temperatures of 300 and 77 K. While at × ≥ 0.5 the values of microhardness (Hv) and compression yield stress (σ0.2) in samples after HPT at 77 K are larger than those in samples after HPT at 300 K, for × ≤ 0.2 surprisingly the opposite effect is observed. As in case of the undeformed CoCrFeMnNiVx alloys, the behaviour for vanadium concentrations × ≥ 0.5 can be related to the formation of tetragonal σ‐phase in addition to fcc matrix, while the anomalous behaviour for × ≤ 0.2 arises from the formation of HPT‐induced hexagonal martensitic phase. In the low temperature ranges, i.e. 20 – 300 K in case of HPT nanostructured CoCrFeMnNiV0.2, and 150 – 300 K in case of HPT nanostructured CoCrFeMnNiV0.5, dependences of σ0.2(T) show characteristics of thermally‐activated dislocation movement. For the first time in HEAs ‐ anomalous dependences of σ0.2(T) at temperatures 4.2 – 20 K for CoCrFeMnNiV0.2, and at 80 – 150 K for CoCrFeMnNiV0.5 are found which indicate at the occurrence of non‐thermal inertial dislocation movement.This article is protected by copyright. All rights reserved.

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Comparison of cryogenic deformation of the concentrated solid solutions CoCrFeMnNi, CoCrNi and CoNi

Cited by 48 publications

References 46 publications

High-temperature low cycle fatigue behavior of an equiatomic CoCrFeMnNi high-entropy alloy

High-temperature low cycle fatigue behavior of an equiatomic CoCrFeMnNi high-entropy alloy

Dislocation-based serrated plastic flow of high entropy alloys at cryogenic temperatures

Effect of V Content on the Microstructure and Mechanical Properties of High‐Pressure Torsion Nanostructured CoCrFeMnNiV_x High‐Entropy Alloys

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Comparison of cryogenic deformation of the concentrated solid solutions CoCrFeMnNi, CoCrNi and CoNi

Cited by 48 publications

References 46 publications

High-temperature low cycle fatigue behavior of an equiatomic CoCrFeMnNi high-entropy alloy

High-temperature low cycle fatigue behavior of an equiatomic CoCrFeMnNi high-entropy alloy

Dislocation-based serrated plastic flow of high entropy alloys at cryogenic temperatures

Effect of V Content on the Microstructure and Mechanical Properties of High‐Pressure Torsion Nanostructured CoCrFeMnNiVx High‐Entropy Alloys

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Effect of V Content on the Microstructure and Mechanical Properties of High‐Pressure Torsion Nanostructured CoCrFeMnNiV_x High‐Entropy Alloys