CHARACTERISTICS OF AN AMORPHOUS MAGNETIC ALLOY LAYER PREPARED BY LASER QUENCHING, AND ITS APPLICATION TO A TORQUE SENSOR

To fabricate an amorphous magnetic alloy layer, an Fe78B13Si9 crystalline layer firmly fixed on a stainless steel substrate by silver brazing was melt quenched by laser irradiation. The laser-quenched layer consisted mainly of the amorphous single phase with an orderly striped pattern, divided by the heat-affected zones. The vibrating sample magnetometry measurements indicated that the laser-quenched layer had the magnetic easy direction along the direction of the laser scan. Taking into account the magnetic anisotropy, the laser-quenched layer was utilized to construct a non-contact-type static torque sensor. It was found that the sensitivity and the linearity were very good when the laser beam was scanned parallel to the direction of maximum stress induced on the shaft surface by the applied torque.