A Study on Crystallization Mechanism and Effects of Heat Treatment on the Structure and Magnetic Properties of Co68.15Fe4.35Si12.5B15 Amorphous Ribbons

Amorphous Co68. 15Fe4. 35Si12. 5B15 ribbons were prepared by planar flow casting process and characterized by x-ray diffractometry (XRD)، differential thermal analysis (DTA) and magnetic measurements. Activation energy of amorphous to crystallization transition was estimated at various heating rates by two well-known Kissinger and Augis & Bennet (A&B) methods using DTA results، and was found to be around 673. 5 kJ/mol. The magnetic properties of amorphous ribbons heat treated under protective gas atmosphere at temperatures in the range of 300-560 °C for 15 to 60 minutes revealed that the annealing of as-spun ribbons up to 400 °C leads to an increase in the magnetic saturation induction، while severe deterioration of soft magnetic properties were observed with further increasing the temperature، due to formation of some crystalline phases، such as cobalt solid solution، Fe23B6 and Co13B7 phases.