Mechanism of Amplitude-Dependent Internal Friction in Metals

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The conventional method of data analysis on internal friction was criticized in detail, and its scope and limitation were explicitly indicated. Instead of usual data on the temperature dependence of internal friction, the amplitude and frequency dependence of internal friction was analysed on the basis of phenomenological theory. The results obtaind are summarized as follows:(1) In the general case of inhomogeneous deformation of specimens, the measured value of amplitude-dependent internal friction was expressed in terms of not only physical properties of the material but also experimental conditions of the apparatus.(2) For metals and alloys, internal friction cused by dislocation motion was formulated as a function of amplitude and frequency. A remarkable difference in theoretical expression was demonstrated between low and high temperatures(3) The frequency dependence of internal friction was measured below room temperature by the forced vibration method. The carbon Snoek peak was detected in iron at bout 260 K, and the hydrogen relaxation peak was detected in Invar alloy at about 170 K.