Enhancing magnetic properties of the Co66Fe6Si13B15 metallic glass through DC annealing

Abstract

Excellent soft magnetic properties of Co-based metallic glasses (MGs) can be achieved by appropriate annealing treatments. In this study, the Co66Fe6Si13B15 MG was annealed by direct current (DC) with densities ranging from 67 to 333 A/mm2 for varied periods of time. The magnetic properties of both the as-prepared and annealed samples were compared, which were further correlated with microstructure evolution. When the current density is lower than 167 A/mm2, themagnetization increases from 43 emu/g for the as-prepared state to over 60 emu/g for the annealed samples, and the coercivity sharply declined due to the stress release and structural relaxation caused by current annealing. Increasing current density leads to the formation of nanocrystalline particles of the size smaller than 5 nm, and the magnetic properties of the composite material further improve, which could be interpreted in terms of the random anisotropy model. The best soft magnetic performance with Ms of 72 emu/g and Hc of 4 Oe was obtained in the sample after annealed with a current density of 217 A/mm2 for 60 s. Larger grains result in the deterioration of magnetic properties once the current density exceeds 233 A/mm2. The results also imply that high-density but short-time current annealing can realize more efficient and precise treatment with respect to industrial application.