BENDING STRESSES AND BISTABLE BEHAVIOR IN FE-RICH AMORPHOUS WIRE

The aim of this work is to analyze for the first time the changes in m agnetic properties of an Fe-rich amorphous wire (Fe77.5Si7.5B15) when it is submitted to bending stresses. Upon a reduction of the radius of curvature, R(c), of the wire (i.e. increasing bending stresses), the main changes in the magnetic properties are summarized as follows: (a) Bistable behavior disappears when reducing R(c) below about 11 cm but it is again observed for R(c) less than about 2.5 cm. This latter eff ect is also obtained for short wires (less than around 7 cm) which do not show spontaneous bistability. (b) For the case when bending stress es make bistability disappear, the susceptibility increases more than one order of magnitude with regards to the case of bistable wire, and parallel to the increase of susceptibility, a reduction of remanent ma gnetization is observed. The disappearance and later occurrence of the bistable behavior with increasing bending stresses are discussed in t erms of the tensile and compressive stresses induced when the sample i s bent. The possibility of having bistable wires with toroidal symmetr y is also discussed owing to its interest for particular applications as pulse generators with reduced size and magnetic switches.