Attractive magnetic properties in as-cast bulk metallic glasses

We proposed an in-situ stress release strategy for combing magnetic and mechanic properties in the bulk metallic glass (BMG), via balancing the solidification and microstructure relaxation processes. In this proof-of-concept study, the effectiveness is validated in typical Fe-based, FeCo-based, CoFe-based and FeNi-based BMG rings. It was found that the as-cast BMGs with superior strength and hardness exhibit excellent soft-magnetic properties without annealing, including a super-low coercivity of 1.4–2.9 A/m, high effective permeability of 3.3–13.7 k and low loss (P_{50, 200}) of 0.04–0.06 W/kg, which are about 0.8–1.6 %, 14–59 times and 9–12.8 % that of the electrical iron rings, respectively. The magnetic properties are stable at service temperatures of 25–150 °C. The excellent soft-magnetic properties are ascribed to the low anisotropy of the uniform structure and weak pinning effect of the domain. These results pave a new route for evading the annealing induced brittleness dilemma and combining the mechanic-magnetic properties for the advanced BMGs.