Effect of annealing current density on the microstructure of nanocrystalline FeCuNbSiB alloy

The amorphous Fe73.9Nb3.1Cu0.9Si13.2B8.9 alloy has been submitted to current annealing at four different current densities ranging from 3.3×107 to 3.9×107 A/m2. The effect of annealing current density on the structure of the resulting nanocrystalline phase in the same alloy has been studied using in situ wide angle x-ray scattering and small angle x-ray scattering measurements. Some information about the magnetic properties has been obtained from Mössbauer measurements. It is found that higher current density results in significant grain refinement and decrease in the lattice parameter of the nanocrystalline phase, as well as lowering of x-ray contrast between nanocrystalline grains and the amorphous grain boundary phase. These results suggest a variation, with increasing current density, in the composition of the nanocrystalline grains and/or the amorphous grain boundary phase and are corroborated by ex situ Mössbauer spectroscopy measurements on current annealed samples.