Correlation among the amorphous forming ability, viscosity, free-energy difference and interfacial tension in Fe–Si–B–P soft magnetic alloys

Abstract

To clarify the underlying mechanism of effects of P on amorphous forming ability (AFA) for Fe–Si–B–P alloy system, the AFA and melting viscosity of (Fe76Si9B10)(100-x)/95Px (x = 0–3) amorphous alloys measured in the temperature range of 1200–1450 °C by oscillating cup method were investigated. A viscosity hysteresis occurs at about 1350 °C between the heating and cooling processes for all alloys, and the values of viscosity almost increase as P content increases at each measured temperature under cooling process. However, only considering viscosity cannot provide a satisfactory explanation for the trend of AFA for this alloy system. Afterwards, the mechanism was well revealed by calculating the Gibbs free-energy difference and speculating the interfacial tension. In addition, a positive correlation between magnetic properties (coercivity and effective permeability) and the AFA of this alloy system was also founded, which can provide an auxiliary in understanding the mechanism of AFA to some extent. Meanwhile, when x = 3, the alloy shows excellent soft magnetic properties including low coercivity of 0.9 A/m and high effective permeability of 17,000, which is promising for future electromagnetic device application.