Fe-Rich Wires as Elements for Torsion Sensors Based in Torsion Impedance Effect

Abstract

Fe-rich amorphous wires with positive magnetostriction coefficient, employed in the as-quenched state and after being submitted to current annealing treatments with and without an applied torsional stress, show large impedance responses to applied tensional and torsional stresses. This high response can be employed to develop torsion sensitive elements in technological devices. The resistive and reactive components of the impedance were studied for as-quenched and current annealed Fe73.5Si13.5B9Cu1Nb3 wires as a function of applied torsional stresses, i.e., the torsion impedance (TI) effect. The real part of the impedance showed maxima at finite (non-zero) applied torsion for both twist and untwist annealed wires. Large responses, up to 180% for the reactive component of the impedance were obtained at a 100 kHz drive current frequency for the as-quenched wire demonstrating the possibility of using these wires based on the TI effect as a torsion sensor. Results can be explained taking into account the influence of the annealing treatment on the domain structure, magnetostriction, and magnetic parameters of the amorphous wire.