© 1981 The Japan Institute of Metals

Strain-amplitude (γ ) dependence of damping capacity (Q^{-1}) and rigidity modulus (f^{2}) 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 f^{2} vs γ are characterized by a convex type function, which has a maximum (Q_{max}^{-1}=0.023) at the surface shear γ ∼eq 6× 10^{-5}, and by a concave type function having a minimum (f_{min}^{2}) at nearly the same γ as at Q_{max}^{-1}, respectively. The γ _{p}^{'} and γ _{p}^{''}, which stand for the respective γ levels at Q_{max}^{-1} and f_{min}^{2}, 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 Q_{max}^{-1} is considerably low (Q_{max}^{-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 H_{c} (coercive force), and therefore the difference in the damping property between Ni and SIA may also be ascribed to the relative magnitude of H_{c}.

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.

© 2002 The Japan Institute of Metals

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