Comparison of the dynamic magnetomechanical properties of Tb0.27Dy0.73Fe2 and Tb0.30Dy0.70Fe2

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Abstract
Comparison is made between the magnetomechanical properties of Tb0.27Dy0.73Fe2 (27 Tb) and Tb0.30Dy0.70Fe2 (30 Tb), two commercially available compositions of the giant magnetostrictive alloy Terfenol‐D. The quasi‐static magnetostriction (as a function of bias field) and the dynamic strain coefficient (as a function of bias field and frequency) are shown for the two compositions at room temperature, using stress bias values of 0 and 9 MPa. The energy loss per cycle as a function of frequency is also given. The data for the static magnetostriction versus bias field shows 30 Tb to exhibit a significantly greater increase in initial slope and saturation strain when stress bias is applied compared to that seen for 27 Tb, which possesses superior magnetostriction at zero stress bias. A similar trend is observed in the data for the dynamic strain coefficient with 30 Tb again performing better under stress bias. The widening of the static strain hysteresis loop observed for stressed 30 Tb is seen to manifest itself in the low frequency energy loss per cycle; however 27 Tb is observed to possess the higher eddy current loss at 1 kHz. Data for the ratio d/χ, a quantity which is dependent only on magnetization processes and material constants, are shown which suggests that the application of a stress bias affects the magnetization processes, but differently for the two compositions.