Magnetostriction in Fe/sub 76.5-x/Cu/sub 1/Nb/sub x/Si/sub 13.5/B/sub 9/

The temperature dependencies of the effective saturation magnetostriction /spl lambda//sub s/(T) of nanocrystalline Fe/sub 76.5-x/Cu/sub 1/Nb/sub x/Si/sub 13.5/B/sub 9/ (x=2,3 and 5) ribbons were measured for the samples which were annealed at 480, 500, 520 and 530/spl deg/C. The nanostructure of the samples were characterized using X-ray diffraction measurements. In Fe/sub 76.5-x/Cu/sub 1/Nb/sub x/Si/sub 13.5/B/sub 9/ (x=2, 3 and 5) no change of sign of the effective magnetostriction was found. On the contrary Fe/sub 73.5/Cu/sub 1/Nb/sub 3/Si/sub 16.5/B/sub 6/ ribbon annealed at 530/spl deg/C, shows at elevated temperatures a compensation point in /spl lambda//sub 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.