NMR study of rapidly quenched crystalline and amorphous Fe-B alloys

摘要

Amorphous and microcrystalline Fe-B alloys (4-25 at % B) obtained by rapid quenching of the melt were studied using the pulsed nuclear magnetic resonance (NMR) of B-11 nuclei at 4.2 K. Alloy samples were prepared from both a natural isotope mixture and a mixture of the Fe-56 and B-11 isotopes. The NMR spectra were measured as a function of the boron content. The maximum hyperfine fields at the B-11 nuclei sites are 25-29 kOe and overlap the values of the hyperfine fields at the B-11 nuclei sites in the tetragonal and orthorhombic Fe3B phases and also in the alpha-Fe phase containing boron as a substitutional impurity. The short-range order and local atomic structure of the amorphous Fe-B alloys were determined. The amorphous alloys are found to consist of microregions (clusters) with a short-range order similar to that in the tetragonal or orthorhombic Fe3B phase or the alpha-Fe phase.