Characteristics of an Amorphous Alloy Layer Prepared by Laser-Quenching, and Its Application to a Torque Sensor

An amorphous alloy layer prepared by a laser-quenching technique was employed in the construction of a magnetostrictive torque sensor. Fe78B13Si9 amorphous alloy layers were produced on stainless steel substrates by laser-quenching. The laser-quenched layers consisted of a mainly amorphous phase, partially including regions crystallized under the influence of heat (heat-affected zones). VSM measurements showed that the amorphous alloy layers have an axis of easy magnetization in the laser scanning direction. Taking account of this magnetic anisotropy, we prepared a torque sensor by scanning a laser beam over the shaft surface at 45° to the shaft axis. The torque sensor thus prepared exhibited sufficient sensitivity and good linearity in detecting static torque.