Metastable phase in annealed amorphous Ni0.8-xFexB0.12Si0.08ribbons: Structural and magnetic studies

Amorphous Ni0.8-xFexB0.12Si0.08ribbons with 0 < X < 0.16 have been prepared by the single roller technique. The samples were characterized by X-ray and DTA studies. Chemical composition has been determined. Magnetic studies were carried out in the rangee 4.2-300 K with 0.5<H<15T and the range 293-800 k with O<H<1 T. The samples crystallized to a f.c.c. Ni-like phase at 446°C and developed into complex borides etc. at 496°C. Samples were heated at . to just above 446°C in order to obtain the f.c.c. phase and then studied. While for x=0 though one has f.c.c. Ni phase it is not magnetic even at 4.2K. However with x=0,024, Tcsharply rises to 460K then rises progressively with the increase in X as in crystalline Ni-Fe alloys. Both Tcand magnetization are much lower in crystallized f.c.c. phase as compared to Fe-Ni alloys. The results are discussed.