Piezomagnetic and ultrasonic properties of the Fe-Cu-Nb-Si-B metallic glass after heat-treatment

An Fe73.5Cu1Nb3Si16.5B6 alloy was cast as an initially amorphous ribbon. The samples about 50-51mm long and 4mm wide were cut out from the 10mm wide and about 15μm thick ribbon and annealed at the temperatures over 300oC (to 550oC) in the transverse magnetic field H⊥ and also without magnetic field (H=0). Before nanocrystallization this alloy exhibits the saturation magnetostriction equal to (20-23)x10-6. The annealing at the temperatures over 400oC in the transverse magnetic field increases the maximum value of the magnetomechanical coupling coefficient (km) from 0.10-0.15 (for as quenched state) to over 0.45. The magnetic anisotropy, introduced during the heat-treatment in the transverse magnetic field, is responsible for the predominant vector rotation mechanism which increases the magnetomechanical coupling and ΔE-effect.