Magnetomechanical coupling in Fe73.5Cu1Nb1Ta2Si13.5B9 alloy strips after annealing up to 700°C and its dependence on magnetic field

A magnetomechanical coupling in the Fe73.5Cu1Nb1Ta2Si13.5B9 metallic glass strips in as-quenched state and after annealing in vacuum at the temperature range from 100 to 700oC was investigated. The maximum values of the magnetomechanical coupling coefficient (k) were obtained after annealing at 450oC (km = 0.38). Decrease of the magnetomechanical coupling (to 0.2 after annealing at 470oC, to 0.15 after annealing at 500oC, and to zero after annealing at 700oC) and a drop of the saturation magnetostriction (αs) of this alby from (23-25) x 10-6 for as-quenched state and after annealing at 450oC to 10 x 10-6 after annealing at 500oC, and to about 2 x 10-6 after annealing at 550oC is connected with the forming of the nanocrystalline phase. The ultrasound velocities in the strips depending on the heat treatment and magnetic bias field were changing from 3600 to 5300 m/s.