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Abstract Laser processing of thermoelectric materials provides an avenue to influence the nano‐ and micro‐structure of the material and enable additive manufacturing processes that facilitate freeform device shapes, a capability that is lacking in thermoelectric materials processing. This paper describes the multiscale structures formed in selenium‐doped bismuth telluride, an n‐type thermoelectric material, from laser‐induced rapid melting and solidification. Macroscale samples are fabricated in a layer‐by‐layer technique using laser powder bed fusion (also known as selective laser melting). Laser processing results in highly textured columnar grains oriented in the build direction, nanoscale inclusions, and a shift in the primary charge carriers. Sparse oxide inclusions and tellurium segregation shift the material to p‐type behavior with a Seebeck coefficient that peaks at 143 µV K–1at 95 °C. With an average relative density of 74%, fabricated parts have multiscale porosity and microscale cracking that likely resulted from low powder layer packing density and processing parameters near the transition threshold between conduction and keyhole mode processing. These results provide insights regarding the pathways for influencing carrier transport in thermoelectric materials via laser melting‐induced nanoscale structuring and the laser processing parameters required to achieve effective powder consolidation and hierarchical structuring in thermoelectric parts.
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Numerical Analysis of the Melt Pool Kinetics in Selective Laser Melting Based Additive Manufacturing of Thermoelectric Powders
Abstract Thermoelectric generators convert heat energy to electricity and can be used for waste heat recovery, enabling sustainable development. Selective Laser Melting (SLM) based additive manufacturing process is a scalable and flexible method that has shown promising results in manufacturing high zT Bi2Te3 material and is possible to be extended to other material classes such as Mg2Si. The physical phenomena of melting and solidification were investigated for SLM-based manufacturing of thermoelectric (Mg2Si) powders through comprehensive numerical models developed in MATLAB. In this study, Computational Fluid Dynamics (CFD)-based techniques were employed to solve conservation equations, enabling a detailed understanding of temperature evolution within the molten pool. This approach was critical for optimizing processing parameters in our investigation, which were also used for printing the Mg2Si powders using SLM. Additionally, a phase field-based model was developed to simulate the directional solidification of the Mg2Si in MATLAB. Microstructural parameters were studied to correlate the effects of processing parameters to the microstructure of Mg2Si.
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- Award ID(s):
- 1527239
- PAR ID:
- 10568072
- Publisher / Repository:
- American Society of Mechanical Engineers
- Date Published:
- ISBN:
- 978-0-7918-8811-7
- Format(s):
- Medium: X
- Location:
- Knoxville, Tennessee, USA
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1115/MSEC2024-124375
