Mechanical amorphization of Fe75Nb10B15 powder: Microstructural and magnetic characterization

The evolution of the amorphous fraction developed during the mechanical alloying of a mixture of pure 75 at.% Fe, 10 at.% Nb and 15 at.% B, XAm, has been followed by different techniques: X-ray diffraction, Mössbauer spectroscopy and magnetic permeability measurements; in order to compare their sensitivity in the detection of small fractions. The values obtained for the amorphous fraction from the three techniques show a roughly linear correlation above ∼20%. The most sensitive technique was Mössbauer spectroscopy (XAm obtained from the low hyperfine field contributions) and the less sensitive technique was X-ray diffraction. The Curie temperature of the amorphous phase increases with the milling time due to a slow and progressive incorporation of boron into this phase and the nanocrystals from the boron inclusions.