Factors Controlling the Thickness of Fe-B-Si-C Amorphous Ribbon in Single-Roller Process.

Abstract

The effects of wheel surface velocity and ejection gas pressure on the ribbon thickness were investigated to determine which factors control the thickness of Fe-B-Si-C amorphous ribbon produced by planar flow casting in the single-roller process. Fe80.5B12Si6.5C1 alloy was cooled rapidly on a wheel made of Cu-lmass%Cr. As the wheel surface velocity increased, the ribbon thickness decreased. Observations of the melt puddle indicated that the length of the melt puddle decreased as the wheel surface velocity increased. On the other hand, the length of the melt puddle increased as the ejection gas pressure increased, which resulted in an increase of the ribbon thickness. Further-more, the experimental results in the present work showed that ribbon formation mainly depended on the thermal effects of the wheel. This means that the contact time (τ) and the heat transfer between the melt puddle and the wheel play important roles in ribbon formation. Thus, it is important that these factors are kept constant during casting to obtain a ribbon with uniform thickness.