Effect of carbon content and annealing on structure and hardness of the CoCrFeNiMn-based high entropy alloys

Stepanov, Nikita; Yurchenko, N.; Tikhonovsky, М.А.; Салищев, Г. А.

doi:10.1016/j.jallcom.2016.06.103

Cited by 231 publications

(78 citation statements)

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“…Selected area diffraction pattern show that the observed carbides were of M 23 C 6 type, and EDS analysis reveals that the precipitates were mainly composed of Cr. The precipitation of Cr- rich M 23 C 6 carbides after annealing at 800 C agrees with previous data on CoCrFeNiMn-C alloys with higher carbon concentrations [47]. The volume fraction of the observed carbides is very low ( 0.2%) letting us to consider the alloy in this condition as a single phase alloy.…”

Section: Effect Of Annealing On Microstructure Of the Cold-rolledsupporting

confidence: 89%

“…Detailed examination on different scales has revealed that the microstructure consisted of fcc solid solution without any other phases. The measured lattice parameter of the fcc phase of the CoCrFeNiMn-1(at.%)C alloy equals to 0.3595 nm, which is slightly higher than the fcc lattice parameter of the carbon-free CoCrFeNiMn alloy (0.3593 nm [47]). The higher lattice parameter of the carbon-containing alloy is most likely due to dissolved carbon.…”

Section: Resultsmentioning

confidence: 67%

“…Therefore, in current work we have studied the effect of thermomechanical processing of CoCrFeNiMn-C alloy, containing z1 at.% of carbon, on microstructure and mechanical properties of the alloys. According to results of [47], the alloy is anticipated to have single fcc phase structure without any second phase (carbide) precipitates. Typical thermomechanical processing scheme, including multipass flat rolling at ambient temperature with subsequent annealing, was used.…”

Section: Introductionmentioning

confidence: 99%

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Effect of thermomechanical processing on microstructure and mechanical properties of the carbon-containing CoCrFeNiMn high entropy alloy

Stepanov

Shaysultanov

Chernichenko

et al. 2017

Journal of Alloys and Compounds

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199

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a b s t r a c tMicrostructural evolution during cold sheet rolling to 80% thickness strain and annealing at 600e1100 C for 30 min of the CoCrFeNiMn high entropy alloy doped with 1 at.% of C and resulting mechanical properties of the alloy are reported. It is shown that in the initial homogenized (24 h at 1000 C) condition the alloy has single fcc phase structure. Cold rolling is accompanied by dislocation slip, deformation twinning and formation of shear bands. Annealing at 600 C after 80% cold rolling results only in partial recrystallization of cold-deformed structure, while an increase of the annealing temperature produces fully recrystallized microstructure. Comparison with the data on undoped CoCrFeNiMn alloy demonstrates that the addition of carbon pronouncedly increases dislocation activity simultaneously retarding deformation twinning during rolling and decreases the fraction of twin boundaries in the annealed condition. The effect of carbon can be attributed to an increase of stacking fault energy of the carbon-containing alloy. Cold rolling results in a substantial strengthening of the alloy; its ultimate tensile strength approaches 1500 MPa, but at the expense of low ductility. Good combination of strength and ductility can be obtained after annealing. For example, after annealing at 800 C, the alloy has yield strength of 720 MPa, ultimate tensile strength of 980 MPa, uniform elongation of 21% and elongation to fracture of 37%. It is shown that the high strength of the annealed alloy can be attributed to (i) strong grain boundary strengthening; (ii) solid solution strengthening by carbon.

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Section: Effect Of Annealing On Microstructure Of the Cold-rolledsupporting

confidence: 89%

Section: Resultsmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of thermomechanical processing on microstructure and mechanical properties of the carbon-containing CoCrFeNiMn high entropy alloy

Stepanov

Shaysultanov

Chernichenko

et al. 2017

Journal of Alloys and Compounds

Self Cite

199

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“…4b and c confirm that the irregularly-shaped carbide is M 7 C 3 while the roughly circular carbide is M 23 C 6 . Similarly, Stepanov et al[29] examined a C-doped…”

mentioning

confidence: 99%

The effect of carbon on the microstructures, mechanical properties, and deformation mechanisms of thermo-mechanically treated Fe40.4Ni11.3Mn34.8Al7.5Cr6 high entropy alloys

et al. 2017

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The effects of cold rolling followed by annealing on the mechanical properties and dislocation substructure evolution of undoped and 1.1 at. % carbon-doped Fe 40.4 Ni 11.3 Mn 34.8 Al 7.5 Cr 6 high entropy alloys (HEAs) have been investigated. X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atom probe tomography (APT) were employed to characterize the microstructures. The as-cast HEAs were coarse-grained and single phase f.c.c., whereas the thermo-mechanical treatment caused recrystallization (to fine grain sizes) and precipitation (a B2 phase for the undoped HEA; and a B2 phase, and M 23 C 6 and M 7 C 3 carbides for the C-doped HEA). Carbon, which was found to have segregated to the grain boundaries using APT, retarded recrystallization. The reduction in grain size resulted in a sharp increase in strength, while the precipitation, which produced only a small increase in strength, probably accounted for the small decrease in ductility for both undoped and C-doped HEAs. For both undoped and C-doped HEAs, the smaller grain-sized material initially exhibited higher strain hardening than the coarse-grained material but showed a 3 much lower strain hardening at large tensile strains. Wavy slip in the undoped HEAs and planar slip in C-doped HEAs were found at the early stages of deformation irrespective of grain size. At higher strains, dislocation cell structures formed in the 19 µm grain-sized undoped HEA, while microbands formed in the 23 µm grain-sized C-doped HEA. In contrast, localized dislocation clusters were found in both HEAs at the finest grain sizes (5 µm). The inhibition of grain subdivision by the grain boundaries and precipitates lead to the transformation from regular dislocation configurations consisting of dislocationcells and microbands to irregular dislocation configurations consisting of localized dislocation clusters, which further account for the decrease in ductility. Investigation of the formation mechanism and strain hardening of dislocation cells and microbands could benefit future structural material design.

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“…Сплав демонстрирует высокую пластичность при комнатной температуре и удивительно высокие прочностные и пластические свойства при криогенных температурах -предел текучести и пластичность в 2 раза выше, чем при комнатной температуре [2,3]. Известно, что свойства сплава могут быть улучшены как за счет термомеханической обработки [11], так и за счет дополнительного легирования [11][12][13] В качестве потенциального легирующего элемента особое внимание привлекает такой элемент внедрения как углерод [11,12], поскольку приводит к значительному упрочнению твердого раствора и может использоваться для изменения механизма деформации из-за сильного влияния на энергию дефекта упаковки ГЦК матрицы [11].…”

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VLIJaNIE REZhIMOV SVARKI TRENIEM S PEREMEShIVANIEM NA STRUKTURU I MEHANIChESKIE SVOJSTVA SPLAVA CoCrFeNiMn-0.9%C

2019

International Workshop "Multiscale Biomechanics and Tribology of Inorganic and Organic Systems" ; Mezhdunarodnaja Konferencija

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Effect of carbon content and annealing on structure and hardness of the CoCrFeNiMn-based high entropy alloys

Cited by 231 publications

References 48 publications

Effect of thermomechanical processing on microstructure and mechanical properties of the carbon-containing CoCrFeNiMn high entropy alloy

Effect of thermomechanical processing on microstructure and mechanical properties of the carbon-containing CoCrFeNiMn high entropy alloy

The effect of carbon on the microstructures, mechanical properties, and deformation mechanisms of thermo-mechanically treated Fe40.4Ni11.3Mn34.8Al7.5Cr6 high entropy alloys

VLIJaNIE REZhIMOV SVARKI TRENIEM S PEREMEShIVANIEM NA STRUKTURU I MEHANIChESKIE SVOJSTVA SPLAVA CoCrFeNiMn-0.9%C

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