Impact of SiC Nanodispersions on the Thermoelectric and Mechanical Properties of Magnetic Co₂MnSi Full-Heusler Alloys

Heusler alloys have attracted increasing attention due to their rich functionalities, among which Co2MnSi, a half-metallic full-Heusler, is expected to be a promising n-type thermoelectric material with a superior power factor. However, the intrinsically high thermal conductivity of Heusler alloys due to their metallic nature limits the enhancement in thermoelectric performance. Therefore, it is crucial to reduce the thermal conductivity while maintaining the high power factor, which is a key strategy to fabricate high-performance Co2MnSi alloys. Here, by incorporating a small amount of SiC nanoparticles into the Co2MnSi matrix, the thermoelectric figure of merit is enhanced by approximately 5-fold from 0.03 to 0.15 at 1025 K, due to a significant reduction in thermal conductivity from 22 to 5 W/mK. The electrical transport properties do not suffer any obvious degradation after incorporation of a significant amount of SiC, while the mechanical strength of Co2MnSi-based alloys is further improved. The thermoelectric device fabricated with Co2MnSi as the thermoelectric legs is validated for solid-state refrigeration. It is also expected to promote the development of Co2MnSi-based thermoelectrics with strong magnetism for new applications with multiple functionalities.