Atomic-scale characterization and modeling of 60° dislocations in a high-entropy alloy

Smith, Timothy M.; Hooshmand, Mohammad S.; Esser, Bryan D.; Otto, F.; McComb, David W.; George, E.P.; Ghazisaeidi, Maryam; Mills, Michael J.

doi:10.1016/j.actamat.2016.03.045

Cited by 198 publications

(88 citation statements)

References 42 publications

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“…The line tension parameter α = 0.123 is obtained from the atomistically-measured edge dislocation line tension in the EAM FeNiCr effective matrix, and is close to the coefficient for elemental Al [82]. The dislocation cores in HEAs show large dissociation distances d > 10b, consistent their relatively low stacking fault energies γ SF (low ab initio estimates, and large stacking fault ribbons observed experimentally [100,101,102]). The minimized parameters of Eqs.…”

Section: Fcc High Entropy Alloysmentioning

confidence: 99%

Solute strengthening in random alloys

et al. 2017

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Random solid solution alloys are a broad class of materials that are used across the entire spectrum of engineering metals, whether as stand-alone materials (e.g. Al-5xxx alloys) or as the matrix in precipitatestrengthening materials (e.g. Ni-based superalloys). As a result, the mechanisms of, and prediction of, strengthening in solid solutions has a long history. Many concepts have been developed and important trends identified but predictive capability has remained elusive. In recent years, a new theory has been developed that builds on one historical model, the Labusch model, in important ways that lead to a well-defined model valid for random solutions with arbitrary numbers of components and compositions. The new theory uses first-principles-computed solute/dislocation interaction energies as input, from which specific predictions emerge for the yield strength and activation volume as a function of alloy composition, temperature, and strain-rate. Being a general model for materials that otherwise have a low Peierls stress, it has broad application and has been successfully applied to Al-X alloys, Mg-Al, twinning in Mg alloys, and recently fcc High-Entropy Alloys. Here, the new theory is presented in a general and systematic manner. Approximations and limiting cases that reduce the complexity and facilitate understanding are introduced, and help relate the new model to various physical features present among the historical array of models. The quantitative predictions of the model in the various materials above is then demonstrated.

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Section: Fcc High Entropy Alloysmentioning

confidence: 99%

Solute strengthening in random alloys

et al. 2017

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“…Therefore, it seems that the low SFE of CoCrFeMnNi HEA is a deterministic factor in the evolution of the defect structure during HPT. It is noted that a recently published study [33] showed that in a CoCrFeMnNi HEA the value of SFE may have a spatial dependence due to the variation of local chemical composition. This effect yields a different degree of dislocation dissociation into partials.…”

Section: Evolution Of Lattice Defect Structure In Cocrfemnni Hea Durimentioning

confidence: 99%

Defect structure and hardness in nanocrystalline CoCrFeMnNi High-Entropy Alloy processed by High-Pressure Torsion

Heczel

Kawasaki

Lábár

et al. 2017

Journal of Alloys and Compounds

114

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An equiatomic CoCrFeMnNi High-Entropy Alloy (HEA) produced by arc melting was processed by High-Pressure Torsion (HPT). The evolution of the microstructure during HPT was investigated after ¼, ½, 1 and 2 turns using electron backscatter diffraction and transmission electron microscopy. The spatial distribution of constituents was studied by energy-dispersive X-ray spectroscopy. The dislocation density and the twin-fault probability in the HPT-processed samples were determined by X-ray line profiles analysis. It was found that the grain size was gradually refined from ~60 µm to ~30 nm while the dislocation density and the twin-fault probability increased to very high values of about 194 × 10 14 m −2 and 2.7%, respectively, at the periphery of the disk processed for 2 turns. The hardness evolution was measured as a function of the distance from the center of the HPT-processed disks. After 2 turns of HPT, the microhardness increased from ~1440 MPa to ~5380 MPa at the disk periphery where the highest straining is achieved. The yield strength was estimated as onethird of the hardness and correlated to the microstructure.

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“…The MD calculations are used for predicting the thermomechanical properties, which computes the materials from a molecular-scale and has a very extensive range of applications [137]. MD is well suited to reproduce the smart amplitude oscillations of atoms in the vicinity of crystal-lattice sites.…”

Section: Calculationsmentioning

confidence: 99%

Science and technology in high-entropy alloys

2018

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As human improve their ability to fabricate materials, alloys have evolved from simple to complex compositions, accordingly improving functions and performances, promoting the advancements of human civilization. In recent years, high-entropy alloys (HEAs) have attracted tremendous attention in various fields. With multiple principal components, they inherently possess unique microstructures and many impressive properties, such as high strength and hardness, excellent corrosion resistance, thermal stability, fatigue, fracture, and irradiation resistance, in terms of which they overwhelm the traditional alloys. All these properties have endowed HEAs with many promising potential applications. An in-depth understanding of the essence of HEAs is important to further developing numerous HEAs with better properties and performance in the future. In this paper, we review the recent development of HEAs, and summarize their preparation methods, composition design, phase formation and microstructures, various properties, and modeling and simulation calculations. In addition, the future trends and prospects of HEAs are put forward.

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Atomic-scale characterization and modeling of 60° dislocations in a high-entropy alloy

Cited by 198 publications

References 42 publications

Solute strengthening in random alloys

Solute strengthening in random alloys

Defect structure and hardness in nanocrystalline CoCrFeMnNi High-Entropy Alloy processed by High-Pressure Torsion

Science and technology in high-entropy alloys

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