Materials Transactions Online

Transactions of the Japan Institute of Metals, Vol. 22 No. 5 (1981) pp.301-308
© 1981 The Japan Institute of Metals

A Consideration of the Strain Amplitude-Dependent Damping and Modulus in Ferromagnetic Metals*

Hisashi Kawabe** and Kaizo Kuwahara***

Strain-amplitude (γ ) dependence of damping capacity (Q-1) and rigidity modulus (f2) in ferromagnetic metals (SIA and Ni) has been investigated by the inverted torsion pendulum method as functions of tensile stress (σ l) and magnetic field (H).
In SIA, curves of Q-1 and f2 vs γ are characterized by a convex type function, which has a maximum (Qmax-1=0.023) at the surface shear γ ∼eq 6× 10-5, and by a concave type function having a minimum (fmin2) at nearly the same γ as at Qmax-1, respectively. The γ p' and γ p'', which stand for the respective γ levels at Qmax-1 and fmin2, coincide with each other at σ l\gtrsim 0, whereas with increasing σ l they gradually separate making themselves larger, and for σ l\gtrapprox 100 MPa, yield a rough relation, γ \p′′∼eq 2γ p. The damping properties as a function of H also have a similar tendency. On the other hand, in Ni, the damping maximumis not observed so clearly as in SIA, and its Qmax-1 is considerably low (Qmax-1=0.009 at γ p∼eq 3× 10-4). The variation of γ p' with increasing σ l and H leads mainly to the change in Hc (coercive force), and therefore the difference in the damping property between Ni and SIA may also be ascribed to the relative magnitude of Hc.
While there has so far been given a qualitative relationship that Q-1∝ γ at γ <γ p', the Q-1 vs γ (<γ p') is more likely described by a quadratic increasing function due to the Δ G-effect than by a linear increasing one, and the greater the Δ G-effect, the more noticeable becomes such an increasing tendency of Q-1.

(Received September 8, 1980)

*This was originally published in Japanese in J. Japan Inst. Metals, 44 (1980), 776.
**Faculty of Engineering, The Hiroshima Institute of Technology, Itsukaichi, Hiroshima 738, Japan.
***Faculty of Engineering, Hiroshima University, Hiroshima 730, Japan.

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