Microstructural Refinement and Performance Improvement of Cast n-Type Bi2Te2.79Se0.21 Ingot by Equal Channel Angular Extrusion

Xiaoming Hu; Xi’an Fan; Bo Feng; Dong Kong; Peihai Liu; Rusong Li; Yanglin Zhang; Guangqiang Li; Yawei Li

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자료유형: 학술저널

저자정보: Xiaoming Hu (Wuhan University of Science and Technology) Xi’an Fan (Wuhan University of Science and Technology) Bo Feng (Wuhan University of Science and Technology) Dong Kong (Wuhan University of Science and Technology) Peihai Liu (Wuhan University of Science and Technology) Rusong Li (Wuhan University of Science and Technology) Yanglin Zhang (Wuhan University of Science and Technology) Guangqiang Li (Wuhan University of Science and Technology) Yawei Li (Wuhan University of Science and Technology)

저널정보: 대한금속·재료학회 Metals and Materials International Metals and Materials International Vol.27 No.8

발행연도: 2021.1

수록면: 3,070 - 3,078 (9page)

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How to form a uniform fine-grained structure in n-type polycrystalline Bi2Te3based alloys to stabilize and improve thethermoelectric properties is the burning issue to be solved. In the present work, equal channel angular extrusion (ECAE)method was used to extrude the cast ingot directly at various temperatures to obtain the BiTeSe polycrystalline bulk alloyswith uniform microstructure. The initial lamellae coarse grains (hundreds microns to several millimeters) were efficiently anduniformly refined to a minimum of 4.07 μm at 703 K, which fully demonstrates the feasibility of grain refinement by ECAEfor cast n-type BiTeSe ingot. The average grain size of the extruded billets rapidly increased from 5.35 to 29.55 μm withthe increase of extrusion temperature from 703 to 823 K. Meanwhile, the behavior of abnormal grain growth became moreevident as the extrusion temperature increased because the growth rate increased more rapidly than the rate of nucleation. As the extrusion temperature increased, the Vickers hardness decreased gradually due to grain coarsening. BiTeSe alloysextruded at 703 K achieved the maximum Vickers hardness of 59.8 HV0.05,which was nearly three times higher than that ofthe initial cast ingot. All extruded BiTeSe billets possessed the much higher dimensionless figure of merit (ZT), comparedwith the initial cast ingot due to the simultaneously optimization of electrical and thermal transport performances caused byECAE process. Finally, the specimen extruded at 823 K achieved the maximum ZT of 0.685 at 383 K.

#Thermoelectric materials · BiTeSe · Equal channel angular extrusion · Grain refinement · Point defects

참고문헌 (3)

참고문헌 신청

O. Yamashita / 2003 / Bismuth telluride compounds with high thermoelectric fgures of merit / J. Appl. Phys. 93:368~374

V. S. Zemskov / 2000 / Growth and investigation of thermoelectric properties of Bi–Sb alloy single crystals / J. Cryst. Growth 212:161~166

Yoshinori Iwahashi / 1996 / Principle of equal-channel angular pressing for the processing of ultra-fine grained materials / Scripta Materialia 35(2):143~146

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