Microstructure studies of amorphous and nanocrystalline (Fe1-xCox)85.4Zr6.8-yMyB6.8Cu1 (x = 0 or 0.1, y = 0 or 1, M = Mo, Nb or Nd) alloys

The amorphous and nanocrystalline (Fe1 xCox)85.4Zr6.8 yMyB6.8Cu1 (x = 0 or 0.1, y = 0 or 1, M = Mo, Nb or Nd) alloys were studied using Mössbauer spectroscopy. We have stated that after the low temperature annealing of the samples the decrease of the average hyperfine field due to the Invar effect was observed. This effect is associated with the increase of atom packing density after the annealing of the samples, which may lead to the noncolinear spin state in some regions. This phenomenon was completely suppressed after substitution of 10% of Fe atoms by Co atoms. At early stages of crystallization of the Fe85.4Zr6.8 yMyB6.8Cu1 (y = 0 or 1, M = Mo, Nb or Nd) alloys, the interfacial zone is poor in iron due to diffusion of Zr, B, Nb, Mo and Nd atoms outside regions where á-Fe fine grains are created. However, the iron content in the amorphous matrix is the same as in the as-quenched state. The iron concentration in the interfacial zone of the nanocrystalline alloys obtained by the accumulative annealing depends on the chemical composition of the as-quenched samples. In the nanocrystalline samples obtained by two-step annealing, the iron content in the interfacial layer is higher than in the amorphous matrix.