Effect of Ni-additions in nanocrystallized FeNiNbCuSiB alloys

Structure and magnetic properties of Fe73.5-xNixNb3Cu1Si13.5B9 (x = 0, 5, 1 0, 15, 20, 25 at.%) amorphous and nanocrystalline alloys were investigated. For studying the magnetic behaviour upon changes of Ni and Fe concentratio ns X-ray, Mossbauer measurements as well as thermomagnetic analyses were pe rformed. The first crystallization temperature at about 545 degrees C was n early independent on the Ni concentrations. The temperature of the second c rystallization stage decreases when Ni content increases. Additions of Ni c ause a small change of the Curie temperature. After annealing at 550 degree s C for Ih a nanocrystalline state was formed which leads to magnetic softe ning of the sample for smaller additions of Ni (a = 0 - 15). The nanocrysta lline structure was not observed for higher Ni contents (x = 20, 25).