DIFFERENT INFLUENCE OF SQUEEZING SURFACES ON ANISOTROPY OF RING CORES AND STRIPS OF Fe-BASED NANOCRYSTALLINE RIBBONS
Beata Butvinová – Pavol Butvin – Marek Kuzminski – Igor Maťko
Soft-magnetic properties of Fe-rich and Si-poor Fe-Nb-Cu-B/P-Si nanocrystalline alloys were investigated. Ar-annealed rib-bon-wound ring cores and straight strips were compared and core loss was measured. Although phosphorus was found to hamper preferred surface crystallization - one of the sources of surface squeezing that leads to poorly controlled hard-ribbon axis anisotropy, P appears to aid the other source - oxidation and thus the surface squeezing persists in P-containing alloys too. Whereas P substitution improved slightly the core loss in 4 at% Si alloy, it worsened the loss in 8 at % Si alloy possibly due to making hysteresis loops of ring core and straight strip different as a consequence of different surface stress condition. Si to P balance thus appears significant for a successful hi-B material.
Keywords: magnetic domain structure, nanocrystalline alloys, power loss, soft-magnetic materials