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

Wanqing Dong,Zheng Zhou,Lijun Zhang,Gong Li,Riping Liu,Mengdi Zhang,Peter Liaw

doi:10.3390/met8100781

Wanqing Dong, Zheng Zhou + Show 5 more

Open Access

https://doi.org/10.3390/met8100781

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Journal: Metals	Publication Date: Sep 29, 2018
Citations: 18	License type: CC BY 4.0

Affiliation: Yanshan University, University of Tennessee at Knoxville

Abstract

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.

Highlights

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 and 35 atomic percent [1,2,3]
If the industrial waste heat, automobile exhaust waste heat and other waste heat are converted through thermoelectric materials, the energy efficiency will be greatly improved, and the energy crisis and environment pollution will be alleviated
The significance of this paper is to provide an exploration of the possibility of the high-entropy alloy as the thermoelectric material

Summary

Introduction

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]. Because of the severe lattice-distortion effect and the points defect, HEAs offer a large amount of complexity, which is conducive to phonon scattering. The phase structure of the HEAs is always highly symmetrical, such as face-centered-cubic (FCC), body-centered-cubic (BCC), and hexagonal-close-packed (HCP) phases It is possible for the new class of materials to reach a high convergence of the bands close to the Fermi level to attain the high Seebeck coefficient values [35,36,37]. The peculiar microstructures and properties of the HEA provide opportunities to obtain the low lattice thermal conductivity and appropriate Seebeck coefficient to achieve a high ZT value and act as a new class. Values peculiar microstructures and to properties the HEA opportunities to obtain lattice thermal conductivity andX-ray appropriate. Of the samples measured in thewere laser thermal analyzer (TC-9000H, Ulvac-Riko, Yokohama, Japan), and the cylindrical samples were cut from the center of the ingots with a diameter of

Experimental Section

Crystal

X-ray diffraction of the theannealed annealed

Thermoelectricproperties propertiesofofthe theYYxxCoCrFeNi

Discussion

Conclusions