On Lattice Distortion in High Entropy Alloys

He, Quanfeng; Yang, Yong

doi:10.3389/fmats.2018.00042

Cited by 117 publications

(60 citation statements)

References 39 publications

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“…Both studies argued that the presence of nanoscale obstacles such as clusters and SROs lead to a high friction stress for dislocation motion. Furthermore, dislocation movement in such a highly distorted lattice does not occur through the usual kink-pair mechanism but via wavy dislocation gliding, which involve a large activation volume and could be the reason for the low rate sensitivity of strain hardening observed in the current work [28].…”

Section: Thermomechanical Analysismentioning

confidence: 78%

“…The Peierls stress, for instance, is such a thermally activated mechanism that does not depend on the amount of plastic strain, but depend more on the elastic constants and size and shape of the unit cell [24]. For a high-entropy alloy, the lattice friction (Peierls stress) can be much higher than for a low alloy FCC metal due to its large lattice distortions, strong solid solution strengthening, and higher interaction energy between dislocations and solute atoms [27,28]. Hong et al [10] and Moon et al [9] have investigated the rate controlling mechanism of the CoCrFeMnNi alloy and reported that its activation volume for deformation is closer to that observed in BCC metals.…”

Section: Thermomechanical Analysismentioning

confidence: 99%

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Effects of Adiabatic Heating and Strain Rate on the Dynamic Response of a CoCrFeMnNi High-Entropy Alloy

Soares

Patnamsetty

Peura

et al. 2019

J. dynamic behavior mater.

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This work presents a comprehensive analysis of the effects of strain and strain rate on the adiabatic heating and the mechanical behavior of a CoCrFeMnNi high-entropy alloy (HEA). In this investigation, compression tests were carried out at quasi-static and dynamic strain rates. The temperature of the specimens was measured using high speed infrared thermography. The high strain rate tests were conducted with a Split Hopkinson Pressure Bar, and the tests at lower strain rates were performed using a universal testing machine. The material exhibited a positive strain rate sensitivity, as true stress-strain plots were shifted upwards with the increase in strain rate. With exception of the isothermal tests, temperature rise and the Taylor-Quinney coefficient (β) were noticeably similar for the investigated strain rates. This study shows that the common assumption that β can be considered 0.9 and constant is possibly not very accurate for the CoCrFeMnNi alloy. The β is influenced by at least strain and strain rate.

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Section: Thermomechanical Analysismentioning

confidence: 78%

Section: Thermomechanical Analysismentioning

confidence: 99%

Effects of Adiabatic Heating and Strain Rate on the Dynamic Response of a CoCrFeMnNi High-Entropy Alloy

Soares

Patnamsetty

Peura

et al. 2019

J. dynamic behavior mater.

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“…Additionally, when BT II was present, the chemical composition varied abruptly from the substrate to the clad (Figure 7), which can facilitate the movement of the FCC/FCC interface and promote BT II formation. The various chemical elements present in the solid solution (Cr, Mo, Nb, and Fe) can greatly distort the crystalline lattice of Ni [50]. The low contests of these elements in the TZ-C/S aid the movement of FCC/FCC interface, producing favorable conditions for an increase in BT II.…”

Section: Crystallographic Texture Of the Clad Layersmentioning

confidence: 99%

Microstructural and Mechanical Characterization of the Transition Zone of 9%Ni Steel Cladded with Ni-Based Superalloy 625 by GTAW-HW

Farias

Filho

Azevedo

2018

Metals

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9%Ni steel was recently used for the first time in the field of injection unit (IU) for the injection of CO2 into oil wells. Because such steels are operated in H2S medium and are susceptible to sulfide stress cracking, their pipes are cladded with Ni-based superalloy 625 by using gas tungsten arc welding with a hot wire to prevent this phenomenon from occurring. The transition zone of substrate/clad can have high hardness and low toughness, and promote failure of the component during service; therefore, it is very important to know its characteristics. In this work, this transition zone was analyzed through optical and scanning electron microscopy with energy dispersive X-ray spectrometry and electron backscatter diffraction, as well as Vickers microhardness, shear and bend tests. Metallographic analysis identified type I and II boundaries with distinct chemical gradients, MC-type carbides, Laves/γ eutectics, peninsulas macrosegregation, crystallographic texture close to <100> in the clads, residual strain, and drop of microhardness across the transition zone. The clads were approved in the shear and bend tests. This work proposes a new type II boundary formation mechanism in dissimilar welds of steels that do not exhibit the allotropic transformation δ → γ during the welding thermal cycle and do not experience a change in the solidification mode.

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“…According to the research works from Toda-Caraballo et al [35] and Owen et al [36], the lattice distortion effect does not show vast improvement in residual strain, which is generated by the deviation of the atomic size, when compared to the conventional alloys [37]. These results are reasonable as vast lattice distortion will lead to phase instability that unable to neutralise by high configuration entropy [38].…”

Section: Severe Lattice Distortion Effectmentioning

confidence: 89%

“…Seven HEA families have been categorised from 408 HEAs by Senkov et al [42], which are 3d transition metal HEAs, refractory metal HEAs, 4f transition metal HEAs, Nobel metal HEAs, interstitial compound HEAs, light metal HEAs, and HEA brasses and bronzes [42]. The descriptions of each HEA family were summarised in Table 2 [28,[31][32][33][34][35][36][37][38][39][40][41]. Senkov et al [42] classified the boron, carbon or nitrogen elements contain interstitial compound as a new family due to the significant microstructure and phase changes triggered by the addition of the elements in 3d transition metal HEAs and refractory HEAs.…”

Section: Major Hea Familiesmentioning

confidence: 99%

UQ eSpace

Koey¹

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The strength of the Fe45Ni25Cr25Mo5 high-entropy alloy was reinforced through precipitation hardening and minor addition of titanium and carbon elements. The aged Fe45Ni25Cr25Mo5 alloy obtained a peak hardness of 307.12 HV at 900 ˚C for 48 hours. This alloy was strengthened through the formation of long thin needle-like ! phase precipitates. 5 at.% of titanium and carbon were added to the alloy respectively to further improve its strength and restrict the growth of the needle-like precipitates during aging treatment. The involvement of the reinforcement content induced the formation of (Ti, Mo, C)-rich carbides, and hence increased the hardness of the alloy to 246.45 HV. Aging treatment was performed in (Fe45Ni25Cr25Mo5)90Ti5C5 alloy to investigate the strength evolution of this alloy. The best aging performance was obtained when the alloy was aged at 800 ˚C for 96 hours with an optimum hardness of 402.24 HV. The minor elemental addition has refined the needle-like precipitates from the size larger than 20 µm to the size smaller than 10 µm. As a result, (Fe45Ni25Cr25Mo5)90Ti5C5 alloy was reinforced by the high volume fraction of fine needle-like precipitates and nanosized precipitates, fine divorced eutectic structures, as well as the (Ti, Mo, C)-rich carbides.

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On Lattice Distortion in High Entropy Alloys

Cited by 117 publications

References 39 publications

Effects of Adiabatic Heating and Strain Rate on the Dynamic Response of a CoCrFeMnNi High-Entropy Alloy

Effects of Adiabatic Heating and Strain Rate on the Dynamic Response of a CoCrFeMnNi High-Entropy Alloy

Microstructural and Mechanical Characterization of the Transition Zone of 9%Ni Steel Cladded with Ni-Based Superalloy 625 by GTAW-HW

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