Magnetomechanical sensing of laserhyphen;generated ultrasound to assess structural change in metallic amorphous ribbons

摘要

A new noncontacting technique is described for monitoring the structural changes in metallic amorphous ribbons. Laserhyphen;generated ultrasound is propagated from a line source, and a magnetomechanical sensing coil is used to monitor the waveform at some distance away from the source. The quality of the ribbon is assessed by either changes in velocity or amplitude of the magnetomechanical signals from the coil, which itself depends on the strength of the applied magnetic field. Metglas 2605 SC has been studied in this way, showing that velocities change from 4940 to 5830 msminus;1as the material becomes progressively less amorphous, while corresponding maximum amplitudes of the sensing coil signal reduce some 18hyphen;fold.