A new high entropy alloy brazing filler metal design for joining skutterudite thermoelectrics to copper

A new High Entropy Alloy (HEA) in the ZnGaCu-(AuSn) system was designed to join skutterudite thermoelectrics (CoSb2.75Sn0.05Te0.20), with a diffusion barrier of Ni applied, to Cu. Such a joint could be part of a device for thermal energy recovery within automotive exhaust systems. A rapid large-scale screening calculation technique based on Python programming has been introduced to conduct the HEA selection process, resulting in a series of alloys, which have been experimentally verified. It is demonstrated that a particular ZnGaCu-(AuSn) HEA alloy can join Ni and Cu successfully; a good joint is formed, and the average electrical contact resistance of the interfaces after joining is promising at room temperature, which shows that it has the potential to improve on the existing fillers used in such applications. The alloy design methodology used here suggests a potential efficient route to design new filler metals for a wide array of applications in which existing filler metals are not suitable.