Mechanism of low thermal conductivity for Fe76Si13B8Nb2Cu1 amorphous and nanocrystalline alloys at room temperature

Abstract Fe-based amorphous and nanocrystalline alloys offer application prospects in the field of coating materials, and their thermal transport property is crucial for their application in thermal insulation coating. However, the mechanism of thermal conductivity in the process of isothermal annealing preparation of Fe-based nanocrystalline alloys are still unclear. In this work, the thermal conductivity of Fe76Si13B8Nb2Cu1 amorphous alloy isochronal annealed at different temperature was examined. It was found that the thermal conductivity of the amorphous alloy is as low as 7.06 W/mK, whereas significantly increases to 10.38 W/mK after annealing at 693 K for 1800s. The result of the limited increase in thermal conductivity at annealing temperatures below the 693 K can be ascribed to the conflicting variations of electronic and phonon contributions with increasing temperature. At annealing temperature above 693 K, the two contributors start to cooperate, leading to abrupt enhancement of thermal conductivity. This work provides an insight into the thermal transport mechanisms for amorphous alloys.