Research on the Thermal Stability of MoCu/CoSb₃ Thermoelectric Junction with CoCrFeNi High-Entropy Alloy Barrier Layer

CoSb₃-based skutterudites are one of the most potential thermoelectric materials in the medium temperature range. However, the fast diffusion rate between traditional alloy electrode materials and CoSb₃-based thermoelectric materials promotes the formation of brittle intermetallic, which will damage the joint performance. To alleviate this problem, high-entropy alloys were chosen as diffusion barriers for thermoelectric joints in this study. Due to the high entropy effect and the sluggish diffusion effect, high-entropy alloys exhibit excellent phase stability and the ability to prevent element diffusion. Therefore, in this study, the vacuum hot pressing sintering technology was used to prepare Mo-Cu/CoCrFeNi/CoSb₃ thermoelectric joints, and the interface microstructure evolution and thermal stability of CoCrFeNi high-entropy alloy as a diffusion barrier layer thermoelectric joint before and after thermal aging were investigated. The results showed that the Mo-Cu/CoCrFeNi/CoSb₃ joint was well bonded, and a stable reaction layer was formed at the CoCrFeNi/CoSb₃ interface. After a long-time aging, the structure and composition of the reaction layer remain unchanged, and the growth of the diffusion layer is relatively slow. The high entropy alloy barrier layer effectively reduces the coarsening rate of the diffusion layer, ensures the structural stability of the thermoelectric joint, and provides a new bonding strategy for the development of high-performance thermoelectric devices.