Anomalous Absorption of Flexural Vibrations in Invar Alloys

Abstract

The magnetic absorption peak of flexural vibrations was experimentally studied for Invar-type alloys, Cu–Ni alloys and also in pure nickel and gadolinium. The absorption peak appearing at the Curie point was observed in Invar and the other metals and alloys, whereas another new peak was found only in Invar and Gd at a temperature below the Curie point. The latter peak appears upon the application of magnetic field, and its shape and location depend strongly on magnetic field. This anomalous peak corresponds to the maximum of linear magnetostriction in Invar, and to the minimum in Gd. It was also observed that the amplitude-independent internal friction decreases with increasing temperature in the magnetically saturated Fe–Ni alloys. This behavior is discussed in connection with the positive thermoelastic coefficient on assuming the application of the Voigt solid model to the alloys.