Enhancing Interfacial Stability and Mechanical Strength of a CoSb₃-Based Thermoelectric Junction Using Ti-Based Alloy...

Area of Science:

• Materials Science
• Thermoelectrics
• Solid-state Chemistry

Background:

• CoSb3-based filled skutterudites (SKDs) are promising thermoelectric materials for power generation.
• Their practical application is hindered by poor interfacial stability and mechanical strength when joined with copper electrodes.

Purpose of the Study:

• To develop multiphase Ti-based alloy barrier layers for CoSb3-based thermoelectric junctions.
• To prevent the formation of brittle TiCoSb phases and enhance interfacial stability and mechanical strength.

Main Methods:

• Designed Ti80NbxCo20 barrier layers (x = 0, 5, 10 at.%) based on coefficient of thermal expansion matching.
• Utilized transmission electron microscopy to analyze interfacial microstructure.
• Conducted aging tests and shear strength measurements on brazed joints.

Main Results:

• Ti-based alloy barrier layers effectively prevented continuous brittle TiCoSb phase formation.
• The interfacial microstructure showed a uniform staggered distribution of various Ti-Sb-Co phases.
• Brazed joints with Ti75Nb5Co20 barrier layers maintained a shear strength of ~21 MPa after aging at 823 K for 360 h.

Conclusions:

• Multiphase Ti-based alloy barrier layers significantly enhance the interfacial stability and mechanical strength of CoSb3-based thermoelectric junctions.
• The developed Cu/CuSnP/Cu/Ti75Nb5Co20/Ce-SKD brazed joint demonstrates excellent performance for power generation applications.