Effect of Co on the microstructure, magnetic properties and thermal stability of bulk Fe73−xCoxNb5Y3B19 (where x = 0 or 10) amorphous alloys

► The paper presents the results of structure, thermal stability and magnetic properties of Fe73−xCoxNb5Y3B19 (where x = 0 or 10) bulk amorphous alloys in the as-cast state in the form of plates with a thickness of 0.5 mm and an area of 100 mm2. ► Results of this study indicate that despite the negative effect of exchange of Fe onto Co, what results in decrease of the saturation of magnetization, Curie temperature and thermal stability, it is clear that such a slight deterioration of these parameters is compensated with a significant reduction of the coercivity field values. ► What testify that amorphous alloys with the addition of Co can be successfully used as magnetic cores in modern medium power transformers.