Zhang Lixia, Pan Hui, Sun Zhan, Geng Huiyuan, Xu Yunsheng, Chang Qing, Zhang Bo
State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China.
ACS Appl Mater Interfaces. 2023 Dec 27;15(51):59912-59919. doi: 10.1021/acsami.3c14591. Epub 2023 Dec 16.
CoSb-based filled skutterudites (SKDs) are among the most promising materials for power generation. However, the poor interfacial stability and mechanical strength severely limit their practical application when joined with Cu electrodes. In this study, we propose multiphase Ti-based alloy barrier layers for CoSb-based thermoelectric junctions to prevent the continuous brittle TiCoSb phase formation. Following the principles of coefficient of thermal expansion matching, we designed three types of TiNbCo ( = 0, 5, and 10, at.%) barrier layers with the thin intermetallic compound (IMC) layers (<20 μm). Transmission electron microscopy analysis revealed that the interfacial microstructure of the TiNbCo/Ce-SKD junction comprises TiSb, TiCoSb, TiCoSb, and TiSb phases, as well as unreacted TiCo, TiCo, and Ti(Nb) phases, demonstrating a uniform staggered distribution state. After aging tests, the IMC thickness increased gradually from 7 to 12 μm, and the interfacial contact resistivity increased from 7.59 to 15.46 μΩ·cm. A Cu layer was chosen as a buffer during the brazing process to prevent the formation of cracks and holes. After aging for 360 h at 823 K, the shear strength of the brazed joints remained at ∼21 MPa. Our results demonstrate that the Cu/CuSnP/Cu/TiNbCo/Ce-SKD brazed joint exhibits excellent interfacial stability and satisfactory mechanical strength.
基于CoSb的填充方钴矿（SKD）是最有前景的发电材料之一。然而，当与铜电极连接时，较差的界面稳定性和机械强度严重限制了它们的实际应用。在本研究中，我们提出了用于CoSb基热电结的多相钛基合金阻挡层，以防止连续脆性TiCoSb相的形成。遵循热膨胀系数匹配原则，我们设计了三种类型的TiNbCo（= 0、5和10，原子百分比）阻挡层，其具有薄的金属间化合物（IMC）层（<20μm）。透射电子显微镜分析表明，TiNbCo/Ce-SKD结的界面微观结构包括TiSb、TiCoSb、TiCoSb和TiSb相，以及未反应的TiCo、TiCo和Ti(Nb)相，呈现出均匀的交错分布状态。经过时效测试后，IMC厚度从7μm逐渐增加到12μm，界面接触电阻率从7.59μΩ·cm增加到15.46μΩ·cm。在钎焊过程中选择铜层作为缓冲层，以防止裂纹和孔洞的形成。在823K下时效360小时后，钎焊接头的剪切强度保持在~21MPa。我们的结果表明，Cu/CuSnP/Cu/TiNbCo/Ce-SKD钎焊接头具有优异的界面稳定性和令人满意的机械强度。
