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

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 781 ◽  
Author(s):  
Wanqing Dong ◽  
Zheng Zhou ◽  
Lijun Zhang ◽  
Mengdi Zhang ◽  
Peter Liaw ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Alternative Energy ◽  
Phonon Scattering ◽  
Waste Heat ◽  
Second Phase ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Alternative Energy Sources ◽  
The Future

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 YxCoCrFeNi, GdxCoCrFeNiCu, and annealed Al0.3CoCrFeNi 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.

scholarly journals The influence of Carbon Nanotubes on the Thermoelectric Properties of Bismuth Telluride

2020 ◽  
Author(s):  
Himyan Akbar ◽  
Khaled Youssef
Keyword(s):  
Carbon Nanotubes ◽  
Thermoelectric Properties ◽  
Bismuth Telluride ◽  
Thermoelectric Materials ◽  
Powder Processing ◽  
Phonon Scattering ◽  
Waste Heat ◽  
High Energy ◽  
Average Grain Size ◽  
Multi Walled Carbon Nanotubes

Thermoelectric materials are devices that have the ability to convert waste heat to electricity. The widespread use of thermoelectric materials is currently limited by the low value their figure-ofmerit (ZT). Bismuth telluride (Bi2Te3) is a promising thermoelectric material in the near room temperature applications that provides a ZT value ~ 1. In order to overcome the limitation of utilizing thermoelectric materials in waste heat recovery, a ZT value > 2 is required. In this current study multi-walled carbon nanotubes (MWCNT) was incorporated into Bi2Te3 bulk matrix system to enhance its mechanical and thermoelectric properties through powder processing techniques. The nanocrystalline Bi2Te3/MWCNT composites were prepared using high energy ball milling and spark plasma sintering (SPS) techniques. The structural characterization and the average grain size of both pristine Bi2Te3 and Bi2Te3/MWCNT was found to be approximately (~ 13 nm) and the average strain was found to be 0.2 using both X-ray Diffraction (XRD) and transmission electron microscopy (TEM) techniques. Vickers Microhardness test shows significant improvement of the nanocomposite hardness up to ~2 GPa as a function of increasing the MWCNT content. As for the dimensionless figure of merit (ZT) of the composite, it is expected to increase above the value of the pure binary Bi2Te3 in the temperature range of 298–498 K the addition of MWCNT increased the ZT value from 0.48 to maximum ZT value to 0.61 at 50oC, while at 150oC the ZT value was measured to be 0.35 and 0.43 for Bi2Te3 and MWCNT/Bi2Te3, respectively. It is considered that the enhancement of the thermoelectric performance of the composite mostly derived from the thermal conductivity, which is reduced by an active phonon-scattering at the MWCNT/Bi2Te3 interfaces.

High-entropy-stabilized chalcogenides with high thermoelectric performance

Science ◽  
2021 ◽  
Vol 371 (6531) ◽  
pp. 830-834 ◽  
Author(s):  
Binbin Jiang ◽  
Yong Yu ◽  
Juan Cui ◽  
Xixi Liu ◽  
Lin Xie ◽  
...  
Keyword(s):  
Thermoelectric Materials ◽  
Performance Optimization ◽  
Figure Of Merit ◽  
Phonon Scattering ◽  
Waste Heat ◽  
Configurational Entropy ◽  
Thermoelectric Performance ◽  
Structural Stabilization ◽  
High Entropy ◽  
Thermoelectric Conversion

Thermoelectric technology generates electricity from waste heat, but one bottleneck for wider use is the performance of thermoelectric materials. Manipulating the configurational entropy of a material by introducing different atomic species can tune phase composition and extend the performance optimization space. We enhanced the figure of merit (zT) value to 1.8 at 900 kelvin in an n-type PbSe-based high-entropy material formed by entropy-driven structural stabilization. The largely distorted lattices in this high-entropy system caused unusual shear strains, which provided strong phonon scattering to largely lower lattice thermal conductivity. The thermoelectric conversion efficiency was 12.3% at temperature difference ΔT = 507 kelvin, for the fabricated segmented module based on this n-type high-entropy material. Our demonstration provides a paradigm to improve thermoelectric performance for high-entropy thermoelectric materials through entropy engineering.

Effect of Electron-Phonon Coupling on Transport Properties of Monolayers of ZrS2, BiI3 and PbI2: A thermoelectric Perspective

2021 ◽  
Author(s):  
Gautam Sharma ◽  
Vineet Kumar Pandey ◽  
Shouvik Datta ◽  
Prasenjit Ghosh
Keyword(s):  
Relaxation Time ◽  
Band Structure ◽  
Transport Properties ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Waste Heat ◽  
Transport Coefficients ◽  
Electrical Energy ◽  
Phonon Coupling ◽  
Electron Phonon Coupling

Thermoelectric materials are used for conversion of waste heat to electrical energy. The transport coefficients that determine their thermoelectric properties depend on the band structure and the relaxation time of...

Use of alternative energy sources in protected agriculture

1982 ◽  
Vol 11 (1) ◽  
pp. 16-20 ◽  
Author(s):  
D. Pasternak ◽  
E. Rappeport
Keyword(s):  
Alternative Energy ◽  
Heat Storage ◽  
Waste Heat ◽  
Space Heating ◽  
Energy Sources ◽  
Soil Warming ◽  
Greenhouse Soil ◽  
Geothermal Waters ◽  
Water Curtain ◽  
Alternative Energy Sources

Low temperature energy sources for protected cropping include geothermal waters, waste heat from Industry, and trapped sunshine; application depends on the recovery of heat from circulating warmed water, either via the soil in which the plants are growing or via the air in the greenhouse. Soil warming pipes and ‘water-curtain’ systems of space-heating have shown promise, but heat storage, either for short periods or longer, remains a problem common to all such schemes.

scholarly journals Alternative Energy Sources

2021 ◽  
Vol 03 (01) ◽  
pp. 58-68
Author(s):  
Charyeva Makhbuba Rizakulyevna ◽  
Keyword(s):  
Alternative Energy ◽  
Energy Sources ◽  
Alternative Energy Sources ◽  
The Future

This article discusses the problems of finding new types of fuel that could be called wasteless and inexhaustible. The issue is being discussed the question of what material and by what methods should humanity receive energy in the future.

Effect of the Annealing Treatment on the Microstructure, Microhardness and Corrosion Behaviour of Al0.3CrFe1.5MnNi0.5 High-Entropy Alloys

2013 ◽  
Vol 748 ◽  
pp. 79-85 ◽  
Author(s):  
L.C. Tsao ◽  
C.S. Chen ◽  
Kuo Huan Fan ◽  
Yen Teng Huang
Keyword(s):  
Corrosion Behaviour ◽  
Dendritic Structure ◽  
Annealing Treatment ◽  
Age Hardening ◽  
High Entropy Alloy ◽  
Second Phase ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Fcc Phase ◽  
Bcc Phase

In this study, an Al0.3CrFe1.5MnNi0.5high entropy alloy was synthesized by arc-melting in Ar. The as-cast alloy ingot was heat treated for 8 h at 650-750°C and then cooled in furnace to investigate the effects of age treatment on the microstructure, hardness and corrosion behaviour. The microstructure of as-cast sample has a typical rich-Cr BCC structure of dendrites, rich-Ni FCC interdendrite phases and a small fraction of cross-like rich-Ni FCC phase within the majority dendritic structure. During annealing treatment at 650°C, the cross-like FCC phase (β-FCC) gradually decreased, dendritic rich-Cr BCC phase transfers to Cr5Fe6Mn8phase, and the AlNi phase precipitated within the matrix dendrites. The interdendritic β1-FCC phases gradually decomposed and transfers to second-phase (β2FCC), and the AlNi precipitated phase coarsen during annealing at 750°C. In addition, Cr5Fe6Mn8phase gradually transfers to rich-Cr BCC phase during slow-cooling process. These precipitation phases in the grain matrix are the main age hardening mechanism. The potentiodynamic polarization of the Al0.3CrFe1.5MnNi0.5high entropy alloys, obtained in 3.5% NaCl solutions, clearly revealed that the corrosion resistance increases and the passive region decreases as annealing temperature increasing.

Microstructure and Properties of Alloys with Equal Atomic Principal Components

2013 ◽  
Vol 765-767 ◽  
pp. 3143-3146
Author(s):  
Yan Ping Wang ◽  
Yu Zhuang ◽  
Jian Chen Li
Keyword(s):  
Solid Solution ◽  
Principal Components ◽  
Argon Atmosphere ◽  
Second Phase ◽  
High Entropy Alloys ◽  
Arc Furnace ◽  
Phase Precipitation ◽  
High Entropy ◽  
Bcc Structure ◽  
Fcc Structure

Four high-entropy alloys are prepared by an arc furnace under argon atmosphere. The microstructure and the properties of the alloys are investigated. The results show that NiCrCuCoFe alloy consists of a single FCC solid solution. When Al presents in the alloys, the microstructures of the alloys change to a BCC+ FCC solid solution. It is indicated that Al element promotes the formation of BCC solid solution, and Si and Mn promote the formation of complicated compounds. The hardness of alloys with BCC structure is higher than that of the alloys with FCC structure. The complicated compounds are formed, the hardness increases further. The highest hardness of the alloys reaches 882 HV due to the strengthening of the second phase precipitation.

scholarly journals High-entropy alloys as high-temperature thermoelectric materials

2015 ◽  
Vol 118 (18) ◽  
pp. 184905 ◽  
Author(s):  
Samrand Shafeie ◽  
Sheng Guo ◽  
Qiang Hu ◽  
Henrik Fahlquist ◽  
Paul Erhart ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermoelectric Materials ◽  
High Entropy Alloys ◽  
High Entropy

scholarly journals The Grain Boundary Wetting Phenomena in the Ti-Containing High-Entropy Alloys: A Review

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1881
Author(s):  
Boris B. Straumal ◽  
Anna Korneva ◽  
Alexei Kuzmin ◽  
Gabriel A. Lopez ◽  
Eugen Rabkin ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Grain Boundary ◽  
Principal Components ◽  
Contact Angles ◽  
Second Phase ◽  
High Entropy Alloys ◽  
Grain Boundary Engineering ◽  
High Entropy ◽  
Tie Lines ◽  
Grain Boundary Wetting

In this review, the phenomenon of grain boundary (GB) wetting by melt is analyzed for multicomponent alloys without principal components (also called high-entropy alloys or HEAs) containing titanium. GB wetting can be complete or partial. In the former case, the liquid phase forms the continuous layers between solid grains and completely separates them. In the latter case of partial GB wetting, the melt forms the chain of droplets in GBs, with certain non-zero contact angles. The GB wetting phenomenon can be observed in HEAs produced by all solidification-based technologies. GB leads to the appearance of novel GB tie lines Twmin and Twmax in the multicomponent HEA phase diagrams. The so-called grain-boundary engineering of HEAs permits the use of GB wetting to improve the HEAs’ properties or, alternatively, its exclusion if the GB layers of a second phase are detrimental.

scholarly journals Severe Plastic Deformation and Phase Transformations in High Entropy Alloys: A Review

Crystals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 54
Author(s):  
Boris B. Straumal ◽  
Roman Kulagin ◽  
Brigitte Baretzky ◽  
Natalia Yu. Anisimova ◽  
Mikhail V. Kiselevskiy ◽  
...  
Keyword(s):  
Solid Solution ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Phase Transformations ◽  
Single Phase ◽  
Materials Science ◽  
Bulk Solution ◽  
Second Phase ◽  
High Entropy Alloys ◽  
High Entropy

This review discusses an area of expertise that is at the intersection of three large parts of materials science. These are phase transformations, severe plastic deformation (SPD), and high-entropy alloys (HEA). First, SPD makes it possible to determine the borders of single-phase regions of existence of a multicomponent solid solution in HEAs. An important feature of SPD is that using these technologies, it is possible to obtain second-phase nanoparticles included in a matrix with a grain size of several tens of nanometers. Such materials have a very high specific density of internal boundaries. These boundaries serve as pathways for accelerated diffusion. As a result of the annealing of HEAs subjected to SPD, it is possible to accurately determine the border temperature of a single-phase solid solution area on the multicomponent phase diagram of the HEA. Secondly, SPD itself induces phase transformations in HEAs. Among these transformations is the decomposition of a single-phase solid solution with the formation of nanoparticles of the second phase, the formation of high-pressure phases, amorphization, as well as spinodal decomposition. Thirdly, during SPD, a large number of new grain boundaries (GBs) are formed due to the crystallites refinement. Segregation layers exist at these new GBs. The concentration of the components in GBs differs from that in the bulk solid solution. As a result of the formation of a large number of new GBs, atoms leave the bulk solution and form segregation layers. Thus, the composition of the solid solution in the volume also changes. All these processes make it possible to purposefully influence the composition, structure and useful properties of HEAs, especially for medical applications.

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