Yb_(0.3)Co_4Sb_(12)/Mo-Cu热电元件的界面结构与界面电阻

Interface Structure and Electrical Property of Yb_(0.3)Co_4Sb_(12)/Mo-Cu Element Prepared by Welding Using Ag-Cu-Zn Solder

通过放电等离子烧结(SPS)实现阻挡层Ti-Al、过渡焊接层Ni与热电臂Yb0.3Co4Sb12的一体化烧结,使用Ag-Cu-Zn共晶合金完成热电元件Yb0.3Co4Sb12/Ti-Al/Ni与Mo-Cu电极的钎焊连接。扫描电镜(SEM)显示出Yb0.3Co4Sb12/Ti-Al/Ni/Ag-Cu-Zn/Mo-Cu接头中各界面结合良好,无裂纹,成分分析发现Yb0.3Co4Sb12/Ti-Al界面存在Al Co、TiCo Sb及Ti Sb2等金属间化合物(IMC)。500℃下等温时效30 d后,Yb0.3Co4Sb12/Ti-Al界面处的金属间化合物厚度无明显变化;Ag-Cu-Zn/Ni界面处Cu、Zn扩散趋于稳定,Cu-Zn扩散层厚度达到约40μm。界面接触电阻测试结果表明,等温时效前后Yb0.3Co4Sb12/Ti-Al/Ni/Ag-Cu-Zn/Mo-Cu元件的界面接触电阻率均低于10μΩ·cm2。

The barrier layer of Ti-A1 and the contact layer of Ni were joined to Ybo.3Co4Sb12 simultaneously by us- ing spark plasma sintering （SPS） technique. The Mo-Cu electrode was then welded to thermoelectric element Yb0.3Co4Sb12/Ti-A1/Ni by using Ag-Cu-Zn alloy as solder. SEM results show that there are no cracks at the inter- faces of Yb0.3Co4Sbl2/Ti-A1/Ni/Ag-Cu-Zn/Mo-Cu thermoelectric joints. The EDS analysis shows that intermetallic compounds （IMCs） layer containing A1Co, TiCoSb and TiSb2 phases are formed at the interface between Yb0.3Co4Sb12 and Ti-A1. After thermal aging at 500℃ for 30 d, the inter-diffusions at both Yb0.3Co4Sb12/Ti-A1 inter- face and Ag-Cu-Zn/Ni interface tend to be steady. The contact electrical resistivity of the Yb0.3Co4Sbl2/ Ti-A1/Ni/Ag-Cu-ZrdMo-Cu thermoelectric joints are about 6.1μcm^2 after welding, and it maintained as low as 10μΩcm^2 even after thermal aged for 30 d.