Study of Acoustic Attenuation Trends in Permendur 49 Magnetostrictive Material

Abstract

The mechanical properties of ferromagnetic materials change when the magnetization level of these materials changes. This phenomenon occurs due to magnetostriction. The change in direction of the magnetic domains is the reason for magnetostriction. In this paper, we hypothesize that the amount of acoustic attenuation in ferromagnetic materials depends on their magnetization level. To prove this hypothesis, a numerical approach is employed and the results compared to previous results in the literature. Permendur, an iron-cobalt alloy that exhibits a large magnetostriction effect, is used for the simulation. The results of the numerical study show that ultrasonic reflection and transmission coefficients in Permendur change in response to changes in the external magnetic field. A comparison between these numerical results and experimental results in the literature allows us to determine the changes in acoustic attenuation due to the magnetic field. The results show that there is an increasing trend at first, and then a decreasing trend, between acoustic absorption attenuation and increasing external magnetic field. This approach would be useful in ultrasonic testing of ferromagnetic materials when the reflected echoes are not detectable due to attenuation.