Metastable phases in recrystallised RE4.5+xFe77-xB18.5 (x=0, 1) nanocomposite ribbons and its dependence on cooling rates

F. D. SACCONE, H. SIRKIN AND F. H. SÁNCHEZ

JOURNAL OF METASTABLE AND NANOCRYSTALLINE MATERIALS

Trans Tech Publications

Año: 2004 vol. 20 p. 482 - 487

1422-6375

Nanocomposite magnetic ribbons of RE4.5+xFe77-xB18.5 (RE= rare earth, x= 0, 1) wereprepared by melt-spinning. Mischmetal alloy was employed as the rare earth component.Nanometric scale crystallisation was obtained by direct quenching onto a copper wheel rotating at asurface velocity of 22 m/s, or after thermal annealing of amorphous ribbons produced at 44 m/s.The presence of a mixture consisting of iron and iron boride phases in crystalline samples wasdetermined by X-ray diffraction and Mössbauer spectroscopy. Diluted RE atoms were found insidethe boride structure. A lattice expansion of 10 % in vol. was estimated for t-(Fe, RE)3B, mainly dueto distortion in the c-axis direction.Magnetic properties of amorphous and crystalline ribbons were measured. Results are discussedin terms of the observed structural changes.