Process-microstructure relationship of laser processed thermoelectric material Bi2Te3
Process-microstructure relationship of laser processed thermoelectric material Bi2Te3
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DOI：
10.3389/femat.2022.1046694
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发表时间：
2022-12
期刊：
影响因子：
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通讯作者：
Cagri Oztan;Bengisu Şişik;Ryan Welch;S. LeBlanc
中科院分区：
文献类型：
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作者：
Cagri Oztan;Bengisu Şişik;Ryan Welch;S. LeBlanc
与传统方法相比，添加制造允许制造定制形状的热电材料，同时最大限度地减少浪费、减少加工步骤和最大限度地提高集成度。建立激光添加剂制造的热电材料的工艺-结构-性能关系有助于提高工艺控制和热电性能。本研究主要研究低温热电材料碲化铋(Bi2Te3)的激光加工。在Bi2Te3粉末压坯上进行了不同参数(激光功率、扫描速度和扫描次数)下的单次熔体轨迹加工。详细分析了熔化方式、晶粒长大、球化形成和元素组成等方面的转变。Bi2Te3的快速熔化和凝固导致了细晶组织，并沿温度梯度方向择优生长。实验结果与模拟的熔池尺寸以及温度梯度与凝固速度之间的关系所产生的晶型转变相吻合。在功率为25W、速度为350 mm/S、扫描次数为5次的条件下，样品的球化程度和气孔率最小，柱状晶组织中位错密度较高。
Additive manufacturing allows fabrication of custom-shaped thermoelectric materials while minimizing waste, reducing processing steps, and maximizing integration compared to conventional methods. Establishing the process-structure-property relationship of laser additive manufactured thermoelectric materials facilitates enhanced process control and thermoelectric performance. This research focuses on laser processing of bismuth telluride (Bi2Te3), a well-established thermoelectric material for low temperature applications. Single melt tracks under various parameters (laser power, scan speed and number of scans) were processed on Bi2Te3 powder compacts. A detailed analysis of the transition in the melting mode, grain growth, balling formation, and elemental composition is provided. Rapid melting and solidification of Bi2Te3 resulted in fine-grained microstructure with preferential grain growth along the direction of the temperature gradient. Experimental results were corroborated with simulations for melt pool dimensions as well as grain morphology transitions resulting from the relationship between temperature gradient and solidification rate. Samples processed at 25 W, 350 mm/s with 5 scans resulted in minimized balling and porosity, along with columnar grains having a high density of dislocations.