Influencing factors on the amorphous phase formation in Fe–7.7 at% Sm alloys solidified by high-speed melt spinning

Abstract

The metastable SmFe12 stoichiometric compound has been reported to have superior magnetic properties to the traditional Nd2Fe14B intermetallic compound that can be massively produced by the widely used melt-spinning technique. However, there have been no reports on the successful synthesis of the bulk metastable SmFe12 or amorphous phase with the composition of Fe–7.7 at% Sm (the SmFe12 phase composition) via the aforementioned technique. In the present study, the binary Fe–7.7 at% Sm melt was spun onto a high-speed single Cu roller under various processing conditions. The influencing factors, e.g., the diameter of the nozzle orifice, the ejection gas pressure, and the species of the chamber gas, were examined to clarify the production condition of the amorphous ribbon. It has been confirmed that the careful control of the processing conditions enables the binary Fe–7.7 at% Sm melt to be spun into amorphous ribbons. Based on the in-situ observation of a high-speed video (HSV) camera, a simple model that illustrates the separation of the ribbon from the melt reservoir was proposed, from which the cooling curves of ribbons with different thickness were calculated. Further analysis indicated that both the model and the numerical calculation results agree well with the high resolution TEM observations near the free surface and the roller sides in terms of the structure formation.