The improvement of surface quality and thickness stability of Fe_(78)Si_9B_(13) melt-spun ribbons by melt overheating

The influence of melt overheating on the viscosity of the melt and surface quality of the Fe₇₈Si₉B₁₃ melt-spun ribbons have been studied by using oscillating vessel viscometry, X-ray diffraction, transmission electron microscopy, and field emission scanning electron microscopy. A critical temperature T_c (about 1350 °C) of the melt transformation was determined via viscosity measurements during overheating and subsequent cooling processes. The Fe₇₈Si₉B₁₃ amorphous ribbons were produced through planar flow melt spinning in the temperature range of 1300–1550 °C. A detailed analysis of overheating effects on the melt viscosity and surface features of the as-spun ribbons were performed to rationalize the correlation between the melt state and surface quality of the ribbons. It was found that the enhanced homogeneity of the melt can be achieved by the overheating treatment higher than the critical temperature, which in turn improves the surface quality and thickness stability of the Fe₇₈Si₉B₁₃ melt-spun ribbons.