Origin of ductile–brittle transition of amorphous Fe78Si9B13 ribbon during low temperature annealing

Samples of amorphous Fe78Si9B13 ribbon were annealed at various temperatures well below the crystallization temperature (Tx). The bend test on them was performed. The samples were studied using XRD, DSC and SEM. The results of both the bend test and fracture surfaces manifest that the ductile–brittle transition of the ribbon occurs between 250 and 275 °C. The FeSi-type structure, detected by XRD, forms in this annealing temperature range and disappears beyond that. These investigations suggest that the FeSi-type structure is the origin of the ductile–brittle transition of the ribbon.