Vibrating-reed measurements of the Δe effect and internal friction of the higly magnetostrictive alloy Fe₂(Tb_0.2Dy _0.22Ho_0.58)

Abstract

The large ΔE effect exhibited by the alloy Fe2(Tb 0.2Dy0.22Ho0.58) has been measured dynamically at low frequencies under conditions which closely approach quasistatic equilibrium. It is found that, in common with several other materials, Young's modulus E passes through a distinct minimum as a function of magnetizing field. The modulus minimum is most apparent during initial magnetization, but occurs with reduced prominence and with typical hysteresis as the material is cyclically magnetized. The origin of the minimum is reviewed in terms of the behavior of the macroscopic ΔE effect, and the frequency above which the minimum is expected to disappear from the measured response is discussed in terms of the theory of stress-induced macroeddy currents. The magnetoelastic internal friction exhibits unexplained features which indicate a need for further study of these alloys.