Effect of cooling rate on the microstructure and thermal conductivity of 5 at Cu�Bi2Te3

Legese, SS and Chandravanshi, D and Gadhavajhala, SSS and Pal, V and Serbesa, AT and Srinivasan, B and Olu, FE and Tiwary, CS (2024) Effect of cooling rate on the microstructure and thermal conductivity of 5 at Cu�Bi2Te3. In: Journal of Materials Science .

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Abstract

The quest to enhance the performance of Bi2Te3 material has led to the adoption of various strategies, including (a) the utilization of doping processes and (b) modifying the cooling rate during melt solidification. Therefore, in this work, we selected a Bi-Cu-Te (5 at Cu- Bi2Te3) alloy system and brine-ice (BTC-Bq) and food-grade oil (BTC-Oq) as the quenching mediums to achieve different cooling rates. 5 at Cu-Bi2Te3 was prepared using flame-furnace-melting followed by quenching in these two mediums. This strategy aids in reducing thermal conductivity and improving mechanical hardness. SEM micrographs of both the BTC-Bq and BTC-Oq alloys show a microstructure containing a Bi2Te3 matrix and secondary phase of Cu2�xTe (Cu1.25Te for BTC-Bq, Cu1.5Te for BTC-Oq). Further on studying the thermoelectric properties of these quenched materials, cooling rates introduce defects in the microstructures that act as scatterers, resulting in the reduction of thermal conductivity. Compared to the air-cooled alloy (BTC-AC), BTC-Bq and BTC-Oq alloys exhibit a thermal conductivity reduction of � 64 (� 1.396 W/mK) and � 62 (1.48 W/mK) at 300 K, respectively. Additionally, owing to the Cu segregation at the interphases and the formation of secondary phases in these alloys, the highest Vickers hardness value of �1.28 GPa was achieved for brine-quenched compared to the oil, air-cooled, and other Bi2Te3-based alloys. Overall, the strategy of utilizing different cooling rates (quenching) ensured in achieving lower thermal conductivity and improving the mechanical hardness in 5 at Cu-Bi2Te3 alloy systems. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.

Item Type:	Journal Article
Publication:	Journal of Materials Science
Publisher:	Springer
Additional Information:	The copyright for this article belongs to the publisher.
Keywords:	Bismuth alloys; Brinell Hardness; Calcium alloys; Copper alloys; Rockwell hardness; Thermal conductivity of solids; Vickers hardness, Alloy system; Cooling rates; Doping process; Food grade oil; Mechanical hardness; Melt solidification; Performance; Quenching media; Secondary phase; Thermal, Quenching
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	18 Oct 2024 04:16
Last Modified:	18 Oct 2024 04:16
URI:	http://eprints.iisc.ac.in/id/eprint/86361

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