Microstructure and Some Magnetic Properties of Nanocrystalline Fe73.5-xCoxCu1Nb3Si13.5B9 Alloys

The microstructure and magnetic properties, I,e. the initial susceptibility, coercivity and saturation magnetic polarization of nanocrystalline Fe73.5-~CoxCuiNb3Sii3.5Bi (x = 0 or 7) alloys with different volume fractions of crystalline and amorphous phases, are investigated. The crystalline phase in both conventionally annealed alloys (823 K for 1 h) has D03 ordered structure. However, after the accumulative annealing of the samples (823 K for 5 s and then 10 and 60 min) only short range order in the crystalline phase is observed. The replacing of 7it Fe atoms by Co atoms in the Fe73.5CuiNb3Si13.5Bg alloy leads to the slight enhancement of the magnetic saturation polarization for both as-quenched and nanocrystalline samples. Moreover, the initial susceptibility distinctly increases and disaccommodation as well as coercivity decrease with annealing time for both investigated alloys. This behaviour is attributed to the annealing out of &ee volumes in the amorphous matrix and the increase of the volume fraction of the crystalline phase. Furthermore, the results reported in this