magnetostrictive material
According to the composition, magnetostrictive materials can be divided into metal magnetostrictive materials and ferrite magnetostrictive materials. Metal magnetostrictive materials have low resistivity, Saturation flux density High, magnetostriction coefficient λ Large（ λ =Δ l / l ， l Is the original length of the material, Δ l In magnetic field H Length change under action), used for low-frequency high-power transducer, can output larger energy. Ferrite magnetostrictive materials have high resistivity and are suitable for high frequency applications, but their magnetostrictive coefficient and magnetic flux density are lower than those of metal magnetostrictive materials. Ni Zn Co ferrite magnetostrictive material due to magnetostrictive coefficient λ And has been widely used. Magnetostrictive materials are commonly used in engineering to make various ultrasonic devices, such as The ultrasonic generator , ultrasonic receiver, ultrasonic flaw detector, ultrasonic drill, ultrasonic welding machine, etc; Echo devices, such as sonar , echo detector, etc; Mechanical filter Mixer, pressure sensor, ultrasonic delay line, etc. 
