Dependence of some properties on thickness of smooth amorphous alloy ribbon

Smooth amorphous alloy ribbon, of nominal composition Fe80B14.5Si3.5C2, has been cast 2.54 cm wide in an average thickness range 13≤t≤80 μm. Since the ribbon samples made were largely devoid of underside liftoff areas (gas pockets), the properties measured are not affected by these surface asperities. Most ribbon of the present study has been cast on a copper‐base wheel, while some has been made on a tool steel wheel. Magnetic, thermal, mechanical, and other measurements have been conducted as has x‐ray diffraction of the upper and lower ribbon surfaces. Results indicate that properties characteristic of the amorphous state at first change rapidly and then more gradually with increased ribbon thickness. The limited number of ribbon samples cast on the tool steel wheel tend to exhibit greater brittleness but the same stress relaxation and Curie temperature as equivalent samples made on the copper‐base wheel. Measured properties are discussed in terms of structural relaxation caused by average ribbon cooli...