Dislocation avalanche mechanism in slowly compressed high entropy alloy nanopillars

Hu, Yang; Shu, Li; Yang, Qun; Guo, Wei; Liaw, Peter K.; Dahmen, Karin A.; Zuo, Jian‐Min

doi:10.1038/s42005-018-0062-z

Cited by 35 publications

(20 citation statements)

References 37 publications

(56 reference statements)

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“…The critical exponents, κ and β, were determined by tuning them until the curves collapsed, and were found to be consistent with the predicted MFT values of 1.5 and 0.5, respectively [222]. Hu et al examined the serrations in the compressed nanopillars composed of the Al0.1CoCrFeNi HEA [160]. For the experiments, pillars with diameters of 500-700 nm underwent in situ compression tests, using direct electron imaging.…”

Section: Al01cocrfeni Heamentioning

confidence: 81%

“…The in situ nanomechanical indentation and TEM results for the Al0.1CoCrFeNi HEA in terms of the (a) stress vs. time data (stages I, II, and III labeled in the figure), the TEM imaging results for the serrations that occurred during (b) stage I, (c) stage II, and (d) stage III (with color-coded deformation stages), and (e) the SEM image of the deformed nanopillar that confirms that large crystal-slip ensued during the experiment (reproduced from Reference[160]). …”

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confidence: 85%

“…Furthermore, the TEM characterization indicated that nanoscale-deformation twins leading to the {111} <110> primary slip system were the primary deformation mechanisms responsible for the serrated flow during compression. Hu et al examined the serrations in the compressed nanopillars composed of the Al 0.1 CoCrFeNi HEA [160]. For the experiments, pillars with diameters of 500-700 nm underwent in situ compression tests, using direct electron imaging.…”

Section: Al01cocrfeni Heamentioning

confidence: 99%

“…The stress vs. strain curve for the in situ TEM nanopillar compression tests for the Al 0.1 CoCrFeNi HEA (reproduced from Reference[160]). …”

mentioning

confidence: 99%

“…(a) The plots of the stress-binned CCDF of slip sizes as a function of the stress level over the maximum stress samples with diameters ranging from ~512 to 655 nm, compressed at a strain rate of 1 × 10 −3 s −1 and with similar load-displacement characteristic. (b) The scaling collapse of the same data with the predicted scaling function (reproduced from Reference[160]). …”

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confidence: 99%

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A Review of the Serrated-Flow Phenomenon and Its Role in the Deformation Behavior of High-Entropy Alloys

Brechtl

Chen

Lee

et al. 2020

Metals

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High-entropy alloys (HEAs) are a novel class of alloys that have many desirable properties. The serrated flow that occurs in high-entropy alloys during mechanical deformation is an important phenomenon since it can lead to significant changes in the microstructure of the alloy. In this article, we review the recent findings on the serration behavior in a variety of high-entropy alloys. Relationships among the serrated flow behavior, composition, microstructure, and testing condition are explored. Importantly, the mechanical-testing type (compression/tension), testing temperature, applied strain rate, and serration type for certain high-entropy alloys are summarized. The literature reveals that the serrated flow can be affected by experimental conditions such as the strain rate and test temperature. Furthermore, this type of phenomenon has been successfully modeled and analyzed, using several different types of analytical methods, including the mean-field theory formalism and the complexity-analysis technique. Importantly, the results of the analyses show that the serrated flow in HEAs consists of complex dynamical behavior. It is anticipated that this review will provide some useful and clarifying information regarding the serrated-flow mechanisms in this material system. Finally, suggestions for future research directions in this field are proposed, such as the effects of irradiation, additives (such as C and Al), the presence of nanoparticles, and twinning on the serrated flow behavior in HEAs.

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Section: Al01cocrfeni Heamentioning

confidence: 81%

mentioning

confidence: 85%

Section: Al01cocrfeni Heamentioning

confidence: 99%

“…The stress vs. strain curve for the in situ TEM nanopillar compression tests for the Al 0.1 CoCrFeNi HEA (reproduced from Reference[160]). …”

mentioning

confidence: 99%

mentioning

confidence: 99%

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A Review of the Serrated-Flow Phenomenon and Its Role in the Deformation Behavior of High-Entropy Alloys

Brechtl

Chen

Lee

et al. 2020

Metals

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Phase Selection, Lattice Distortions, and Mechanical Properties in High‐Entropy Alloys

et al. 2020

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Increasing demand for improved physical, chemical, and mechanical properties led to the development of conventional alloys from single elements. These conventional alloys are made by selecting one or two major elements with desired properties, and other minor components are added to tune the properties to meet performance specifications. The conventional alloy design strategy is mainly based on the "solutesolvent" principle. However, another alloy design strategy based on multiprincipal elements in the near-equimolar ratio has recently been developed. In this multiprincipal element system, it is difficult to distinguish between the solute and the solvent, and various atoms are supposed to be randomly distributed in the crystal lattices (which has not been confirmed yet). This strategy, proposed by Yeh [1] and Cantor, [2] was based on the Boltzmann hypothesis of the relationship between entropy and system complexity. They proposed that the increased configurational entropy of mixing in alloys with multiple alloying elements in near-equiatomic proportions would overcome the enthalpy of compound formation, stabilizing solid solutions (SS) at the expense of intermetallics (IMs) during solidification. These multiprincipal element alloys are named "high entropy alloys" (HEAs), although the exact values of entropy in HEAs have not been experimentally measured yet. Since then, hundreds of HEAs with different combinations have been developed based on transition metals, refractory metals, and compound forming elements. [2-20] Most of these HEAs have been found to possess simple crystal structures such as the face-centered cubic (fcc) Fe-Co-Cr-Mn-Ni HEAs, [2] bodycentered cubic (bcc) Al-Co-Cr-Fe-Ni HEAs, [18] and the hexagonal close-pack (hcp) Ho-Dy-Y-Gd-Tb HEAs [6] when solidified from the melts. Experimental characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), nanoindentation, tensile, wear-and corrosionresistance tests have been used to study the microstructureproperties correlations of HEAs. [3-50] These studies have revealed that HEAs possess superior properties, such as high hardness and strength, [23-29] superior corrosion and wear resistance, [3,30-35] good magnetic properties, [9,36-39,51] structural stability, [7,40,41] attractive mechanical properties at extreme temperature conditions, [21,42-47] and good electronic properties. [48,49] Yeh [50] proposed four core effects of HEAs, namely: 1) high-entropy effect; 2) sluggish diffusion effect; 3) sever lattice distortion effect; and 4) cocktail effect, in which the lattice distortion might be the key factor affecting the properties of HEAs. Although a complete understanding of lattice distortions in HEAs is still not established yet, significant progress in HEAs has been made recently.

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Serrated Flow in Alloy Systems

Lebyodkin

Lebedkina

Brechtl

et al. 2021

High-Entropy Materials: Theory, Experiments, and Applications

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Dislocation avalanche mechanism in slowly compressed high entropy alloy nanopillars

Cited by 35 publications

References 37 publications

A Review of the Serrated-Flow Phenomenon and Its Role in the Deformation Behavior of High-Entropy Alloys

A Review of the Serrated-Flow Phenomenon and Its Role in the Deformation Behavior of High-Entropy Alloys

Phase Selection, Lattice Distortions, and Mechanical Properties in High‐Entropy Alloys

Serrated Flow in Alloy Systems

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