Sadami Tomita1 and Hideo Suzuki1
1Hitachi Research Laboratory, Hitachi LTD., Hitachi
In manufacture of amorphous ribbon by the single roll method, there are several unknown factors which affect the ribbon shape i.g. thickness and smoothness. It has experimentally been established that the ribbon shape is influenced by the roll rotating speed, the ejection gas pressure, the nozzle tip profile and the gap distance between the nozzle and the roll, but the mechanism by which these process conditions affect the ribbon shape formation has not been explained yet.
By the observation of a puddle held at the nozzle tip and also by the temperature measurements of the roll and ribbon surface, we can analyze the relationships between the amorphous ribbon shape and process conditions.
Ribbons of Fe70Ni8Si10B12 composition having 10--36 μm thickness were prepared using iron or copper rolls. In experiments in which the rotating speed and ejection pressure were varied, we observed that the puddle stayed in the vicinity of the nozzle tip and the ribbon was extracted from there. Thus, we concluded that the thickness of the amorphous ribbon was determined immediately by the solidified layer and fluid motion layer, while holes and dents on the ribbon surface were caused by gas bubbles caught at the interface between the roll and melt.
amorphous metal, single roll method, rapid quenching, solidification, production condition
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