EN
Influence of composition variations on the physical and chemical properties of rapidly quenched NANOPERM-type, FeNbCuB, and FINEMET-type, Fe(Ni)NbCu(Si)B, alloys in amorphous states, is investigated by Mössbauer spectroscopy, magnetic and electrochemical methods. While the partial substitution of Si for B leads to weak effects, that of Ni for Fe results in pronounced changes of both magnetic properties and chemical stability.