Magnetostriction in Fe76.5-xCu1NbxSi13.5B9

The temperature dependencies of the effective saturation magnetostriction λ_s(T) of nanocrystalline Fe_76.5-xCu₁Nb_xSi_13.5B₉ (x=2,3 and 5) ribbons were measured for the samples which were annealed at 480, 500, 520 and 530°C. The nanostructure of the samples were characterized using X-ray diffraction measurements. In Fe _76.5-xCu₁Nb_xSi_13.5B₉ (x=2, 3 and 5) no change of sign of the effective magnetostriction was found. On the contrary Fe_73.5Cu₁ Nb₃Si_16.5B₆ ribbon annealed at 530°C, shows at elevated temperatures a compensation point in λ_s(T). We suggested two mechanisms to explain this behaviour: (a) for low concentration of Si in bcc-FeSi crystallites, the negative magnetostriction was not still reached; (b) for higher concentration, the Curie temperature enhancement of the amorphous matrix must be considered