Investigation of Low-Temperature Internal Friction

Abstract

The internal friction in pure copper, in copper doped with nickel and gold, and in magnesium, subjected to various amounts of cold work was measured at 40 kc from 4°K to 300°K. Cold work produces a Bordoni relaxation peak in copper at approximately 80°K. The peak position is independent of the amplitude of vibration for strain amplitudes less than 3×10−5. Suitable annealing reduces and eliminates the peak, as does the presence of relatively large quantities of impurities. Increased cold work and impurity additions also systematically reduce the strain amplitude of the internal friction. A peak was found in cold-worked magnesium at 20°K and also a small peak in crystalline quartz at 39°K. A comparison of present theories with these results is given.

Dislocation damping in metals

“…The Deak is either completelyabsent, or very small, as is shown by the measurements of Briggs (1955) and Caswell (1958) on single crystals and of Wilks (1957, 1959a)on polycrystalline material. Small amounts of plastic deformation produce a small peak superposed on a background of internal friction similar to that observed in the annealed material.…”

“…The results of lqiblett and Wilks (1957), Caswell (1958) and Pard (1958) all show that the internal friction associated with the Bordoni peak is approximately independent of the strain amplitude= The greatest range of strain amplitudes has been investigated by Caswell, who used values ranging from 9.3 × 10 -9 to 3-7 x 10 -~ in a specimen wkich had been deformed 5 % by rolling ( fig. 10).…”

“…The internal f~iction of a pure copper single crystal subjected to a reductio~ by rolling of 5~/o. Maximum strain amplitudes: A, 3.7 × 10-5; B, 2-3 × 10-5; C, 9.3 × 10 -s (Caswell 1957). …”

“…(1959) between 1.Sko/s and 6.5 Mc/s; and on single crystals by Caswell (1958) at about 40ko/s, Par~ (1958) at about 5kc/s, and by Thompson and Holmes (1959) at about 16kc/s. The principal results of these investigations are as follows :…”

Acoustic Effects on Cyclic-Tension Fatigue of Al-4Cu-1Mg Alloy by Ultrasonic Shear Wave Methods

“…[18] This material parameter is used extensively for obtaining material characteristics such as lattice-defect structure, phase transformation, glass transition, recrystallization, solid solubility limit, impurities, diffusion, and others. The origin of internal friction can be classified broadly into following categories: [10] (a) point defect, [19] (b) dislocation, [20] (c) grain boundary, [21] (d) complex defect, and (e) quantum effect. Except for the case of (e), which is related to tunneling effect at cryogenic temperature range, other origins are involved in mechanical-relaxation phenomenon of defects in thermally-activated process, scattering of wave energies, and some dynamic interactions.…”