Magnetostriction measurements for amorphous wires

Novel accurate and stable measurement methods for the magnetostriction constant λ_s and the induced anisotropy constant K_u are presented for amorphous wires. The two constants are theoretically expressed using a magnetization rotation model with or without tensile and compressive stresses. Values of flux densities B_s, B _r, and B_m are estimated, observing 60 Hz BH characteristics of the amorphous wire to which a compressive stress is applied in order to realize the magnetization rotation behavior. Measured variations of λ_s and K_u of wires of different compositions for heat treatments with or without stresses are given. A figure of merit for stress sensor constitution is proposed as λ_sB _s/K_u, a maximum value of which is obtained due to a compressive stress anneal for Fe-rich wires