Transmission Mössbauer spectroscopy was used to study changes induced by irradiation of amorphous and nanocrystalline samples. In an as-cast sample neutrons mostly affect the orientation of a net magnetic moment. The average hyperfine field decreases towards higher neutron fluencies. In the case of the nanocrystalline samples a new disordered structure is created in the amorpous remainder corresponding to boride phases as it is shown in the samples isothermally heated from 1 to 8 hours. The structural changes of the amorphous remainder depend on the stage of crystallization and total neutron fluencies.