Influence of heat-treatment and magnetic field on the ultrasound velocities in the Fe72.5Cu1Nb4Sil3.5B9 amorphous ribbons

Ultrasound velocities as the functions of the bias magnetic field and annealing temperature were investigated in the Fe72.5Cu1Nb4Sil3.5B9 alloy. The samples were annealed in vacuum for 1 h in the temperature range from 200 to 700oC The maximum changes were observed after annealing at the temperature of 450oC when the magnetomechanical coupling coefficient reached maximum value (k = 0.62). The ultrasound velocities were ehanging from 3.5 to 5.3 km/s depending on the magnetic bias field and the thermal-treatment history.