Processing of thick ductile metallic glass

The paper reviews the progress made in understanding the effect of processing parameters on ductility of thick cast ribbons of an Fe-B-Si transformer core alloy. The ductile to brittle transition temperature (DBTT) of amorphous ribbons has been studied as a function of their thickness and quenching conditions. Modeling and simulation indicated that ribbon thickness with a given DBTT could be significantly increased by increasing the conductivity of the wheel and improving the heat extraction system. Casts made on wheels modified in this manner allowed for a substantial increase ( > 2 × ) in the thickness of amorphous ribbon that is ductile enough to be processed during manufacturing of stacked core transformers. The thicker ribbon also exhibits attractive low core loss properties. The low coreloss properties of the annealed ribbon have been preserved in stacked transformer corelets.