Co-induced decarburization enhancing corrosion resistance and magnetic properties of Fe-based alloys during annealing

The as-spun and annealed Fe_80-xP₁₃C₇Co_x glassy alloys (x = 0, 4 and 8) were studied by various techniques. The annealed ribbons with x = 0 and x = 4 exhibited surface layer crystallization, whereas the ribbon with x = 8 crystallized in the middle layer. Consequently, the amorphous phase persisted in the middle layer for x = 0 and x = 4 and in the surface layer for x = 8. Reducing Fe₃C content, increasing Fe₃P content and weakening C 1s peak with increasing x indicate that doping Co promoted the decarburization during annealing. The annealed ribbon with x = 8 exhibited a distinct passivation platform and a superior corrosion resistance due to its amorphous surface layer. Additionally, Co doping effectively compensated for or mitigated the magnetic permeability decrease caused by crystallization, allowing the annealed Fe₇₂P₁₃C₇Co₈ ribbon to maintain good soft magnetic properties and ductility. This study can provide some insights for optimizing the performance of Fe-based glassy alloys and expanding their application range.