Structure and magnetic properties of high temperature nanocrystalline Fe–Co–Cu–Nb–Si–B alloys

High temperature nanocrystalline alloys were prepared by partial replacement of iron by cobalt in the Finemet type alloy. The (Fe1–xCox)73.5Cu1Nb3Si13.5B9 (x=0.136–0.68) ribbons were obtained by melt-spinning technique and their chemical composition was determined by means of X-ray microanalyser. The effect of heat treatment, within the temperature range of 733–833 K, on magnetic properties of the alloys was examined. The structure of partially crystallized alloys was investigated using differential scanning calorimetry (DSC), X-ray diffractometry (XRD), and transmission electron microscopy (TEM). The AC (50 Hz) magnetic properties (coercivity, magnetic induction) of the Fe–Co–Cu–Nb–Si–B alloys were also studied. The effect of partial substitution of iron by cobalt on the structure and magnetic properties of the (Fe1–xCox)73.5Cu1Nb3Si13.5B9 alloys annealed in various temperatures and the thermal stability of magnetic properties of the alloys have been discussed.