Local lattice distortion in high-entropy alloys

Song, Haiyang; Tian, Fuyang; Hu, Qing‐Miao; Vitos, Levente; Wang, Yandong; Shen, Jiang; Chen, Nan‐Xian

doi:10.1103/physrevmaterials.1.023404

Cited by 177 publications

(128 citation statements)

References 75 publications

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“…On average, relaxation of internal atomic positions decreases the energies of the fcc and the hcp phases by 17.2 and 20.0 meV/atom, respectively. Such relaxation energies are comparable to other 3d-transition-element-based fcc HEAs [122] as well as the body-centered cubic NbMoTaW HEA [123]. Under the AIM1 in Eq.…”

Section: A Phase Stability and Sfe Of The Interstitial-free Crmnfeconisupporting

confidence: 63%

Impact of interstitial C on phase stability and stacking-fault energy of the CrMnFeCoNi high-entropy alloy

Ikeda

Tanaka

Neugebauer

et al. 2019

Phys. Rev. Materials

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Interstitial alloying in CrMnFeCoNi-based high-entropy alloys is known to modify their mechanical properties. Specifically, strength can be increased due to interstitial solid-solution hardening, while simultaneously affecting ductility. In this paper, first-principles calculations are carried out to analyze the impact of interstitial C atoms on CrMnFeCoNi in the fcc and the hcp phases. Our results show that C solution energies are widely spread and sensitively depend on the specific local environments. Using the computed solution-energy distributions together with statistical mechanics concepts, we determine the impact of C on the phase stability. C atoms are found to stabilize the fcc phase as compared to the hcp phase, indicating that the stacking-fault energy of CrMnFeCoNi increases due to C alloying. Using our extensive set of first-principles computed solution energies, correlations between them and local environments around the C atoms are investigated. This analysis reveals, e.g., that the local valence-electron concentration around a C atom is well correlated with its solution energy.

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Section: A Phase Stability and Sfe Of The Interstitial-free Crmnfeconisupporting

confidence: 63%

Impact of interstitial C on phase stability and stacking-fault energy of the CrMnFeCoNi high-entropy alloy

Ikeda

Tanaka

Neugebauer

et al. 2019

Phys. Rev. Materials

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“…The lattice thermal conductivity decreases with the decrease of the grain size, which is due to the fact that the small grain size will enhance the long wave phonons scattering. The grain size and thermal conductivity of all samples conform to this rule [12][13][14][15].…”

Section: Discussionsupporting

confidence: 62%

“…Traditional alloys include one or two principal elements, but high entropy alloys (HEAs) were defined by Yeh et al as a new class of materials containing five or more principal elements, each with concentrations between 5 atomic percent (at %) and 35 atomic percent (at %) [1][2][3]. Studies have shown that HEAs exhibit some excellent properties, compared with conventional alloys, such as high hardness, great resistance to evaluation wear, corrosion, friction, fatigue, and oxidation [3][4][5][6][7][8][9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

“…The severe lattice-distortion effect is always compared with the traditional alloys, where the lattice site is mainly occupied by the principal element. For HEAs, each constituent element has the same possibility to occupy the lattice sites, since the size of each atom can be different in some cases, which can lead to severe lattice distortion [1,3,15]. Therefore, in the HEAs, the strategies to control phonon scattering can be generally achieved through the complex nature of the materials [34].…”

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confidence: 99%

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Effects of Y, GdCu, and Al Addition on the Thermoelectric Behavior of CoCrFeNi High Entropy Alloys

Dong

Zhou

Zhang

et al. 2018

Metals

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Thermoelectric (TE) materials can interconvert waste heat into electricity, which will become alternative energy sources in the future. The high-entropy alloys (HEAs) as a new class of materials are well-known for some excellent properties, such as high friction toughness, excellent fatigue resistance, and corrosion resistance. Here, we present a series of HEAs to be potential candidates for the thermoelectric materials. The thermoelectric properties of Y x CoCrFeNi, Gd x CoCrFeNiCu, and annealed Al 0.3 CoCrFeNi were investigated. The effects of grain size and formation of the second phase on thermoelectric properties were revealed. In HEAs, we can reduce the thermal conductivity by controlling the phonon scattering due to the considerable complexity of the alloys. The Y, Gd-doped HEAs are competitive candidate thermoelectric materials for energy conversion in the future.The thermoelectric-power generation or refrigeration device made of thermoelectric material has the advantages of being noise free, zero emission and pollution free, lacking vibration, small volume, etc. It has been applied in deep space exploration and refrigeration, and has great potential in waste heat power generation [20,21].Conventional thermoelectric materials currently in use include Bi 2 Te 3 based, PbTe based and SiGe based, etc. Bi 2 Te 3 is currently the most commercially successful thermoelectric material near room temperature. It is widely used in the field of the thermoelectric refrigeration, and is also the thermoelectric material with the highest power generation efficiency at low temperature [22]. Although Bi 2 Te 3 has been commercialized, its performance can be further improved by doping, composition adjustment, etc. PbTe is the medium temperature thermoelectric material that has been studied for the longest time and PbTe-based materials have been successfully used in the NASA aerospace missions many times since 1960. In recent years, PbTe-based thermoelectric materials have made great progress. The application temperature range of the Si-Ge alloy is more than 1000 K. It has been successfully applied to some deep space detectors. For example, in the radioisotope temperature difference battery of the Cassini Saturn detector, the thermoelectric conversion device is prepared by the Si-Ge alloy. However, the reserves of Te and Ge elements are scarce and very costly; Pb is toxic, pollutes the environment, and endangers people's health. Therefore, the development of environmentally friendly, new low-cost thermoelectric materials is particularly urgent.HEAs are always being studied for their mechanical properties. Maybe many new and unexpected properties remain for us to explore. In the search for TE materials, the performance of this kind of material is estimated by the dimensionless figure of merit, defined as ZT = S 2 Tσ/k [23], where S is the Seebeck coefficient, T is the absolute temperature, σ is the electrical conductivity, and k = k e + k l is the total thermal conductivity, where k e and k l are the electronic and lattice co...

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“…Even though the atomic size difference would not be the only factor that can explain the lattice distortion, it has been reported that larger atomic size difference usually causes a larger lattice distortion in HEA. 29 The next question that may be raised from the simulation results in Fig. 2 is why the formation of dislocations and the resultant slip yields the twins in the HEA and binary alloys.…”

Section: Resultsmentioning

confidence: 99%

Understanding the physical metallurgy of the CoCrFeMnNi high-entropy alloy: an atomistic simulation study

et al. 2018

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Although high-entropy alloys (HEAs) are attracting interest, the physical metallurgical mechanisms related to their properties have mostly not been clarified, and this limits wider industrial applications, in addition to the high alloy costs. We clarify the physical metallurgical reasons for the materials phenomena (sluggish diffusion and micro-twining at cryogenic temperatures) and investigate the effect of individual elements on solid solution hardening for the equiatomic CoCrFeMnNi HEA based on atomistic simulations (Monte Carlo, molecular dynamics and molecular statics). A significant number of stable vacant lattice sites with high migration energy barriers exists and is thought to cause the sluggish diffusion. We predict that the hexagonal close-packed (hcp) structure is more stable than the face-centered cubic (fcc) structure at 0 K, which we propose as the fundamental reason for the micro-twinning at cryogenic temperatures. The alloying effect on the critical resolved shear stress (CRSS) is well predicted by the atomistic simulation, used for a design of non-equiatomic fcc HEAs with improved strength, and is experimentally verified. This study demonstrates the applicability of the proposed atomistic approach combined with a thermodynamic calculation technique to a computational design of advanced HEAs.

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Local lattice distortion in high-entropy alloys

Cited by 177 publications

References 75 publications

Impact of interstitial C on phase stability and stacking-fault energy of the CrMnFeCoNi high-entropy alloy

Impact of interstitial C on phase stability and stacking-fault energy of the CrMnFeCoNi high-entropy alloy

Effects of Y, GdCu, and Al Addition on the Thermoelectric Behavior of CoCrFeNi High Entropy Alloys

Understanding the physical metallurgy of the CoCrFeMnNi high-entropy alloy: an atomistic simulation study

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