NONUNIFORMITY IN AMORPHOUS RIBBON DELAY-LINES AFTER STRESS AND CURRENT ANNEALING

Experimental results concerning the reduction of the amplitude nonuniformity of a Metglas 2605SC magnetostrictive delay line (MDL) after stress relief and current annealing under stress are reported. Nonuniformity is defined here as the fluctuation of the peak voltage V0 received by a coil around the MDL at a fixed position versus the distance between the coil and the point of excitation by a pulsed magnetic field, under uniform conditions of bias field and geometry along the length of the MDL. Stress-relieved delay lines were subjected to stress and current annealing. The results show that the fluctuation function was improved for a stress-relieved MDL, subjected to 200 N/mm2 stress and 300 m amps dc longitudinal annealing current. It was also observed that the normalized relationship for V0 versus the exciting pulsed current is the same for any point of excitation under uniform conditions of dc bias field. This could be used to simplify a computational correction of the nonuniformity function.