UNUSUAL MAGNETIC-ANISOTROPY OF SI-POOR FENBCUBSI ALLOYS

If compared to ribbons of standard FeNbCuBSi (13 divided by 16.5 at.% Si) nanocrystalline alloy, different annealing behaviour is displayed if the above alloy contains 10 and less at.% of Si. The most striking difference is observed on samples annealed/nanocrystallized in an atmo sphere (e.g. Ar), where the hard direction is aligned along the ribbon 's long axis. The particular annealing behaviour of magnetic anisotrop y varies with Si contents, with annealing time and yet it differs for vacuum annealing. These peculiarities are studied on a series of Si-po or FeNbCuBSi alloys by magnetic measurements and Mossbauer spectroscop y, consulting DSC and density measurements as well. Some of the abunda nt problems are discussed in detail in this work. The main idea to exp lain the behaviour is based on a squeezing-surface effect which result s in forming of magnetoelastic as well as of stress induced anisotropy .