Damping Peaks in Deformed Nickel

Abstract

The internal-friction spectrum of zone-refined nickel [R(273°K)/R(4.2°K)=600] has been examined at 30 kc/sec, in the temperature range 77°-350 o K. Plastic deformation produces two prominent relaxation peaks, each the sum of several simple peaks. At 30 kc/sec, one peak, which occurs at 138°±7°K, has been identified as the Niblett and Wilks peak, and the other, which has its maximum at 248°±40oK, has been shown to be the Bordoni peak. Both peaks have been studied as a function of cold work, grain size, state of annealing, and strain amplitude.One major result of these studies is a demonstration that the Bordoni peak is only large at low-to-moderate flow stresses and vanishes at high flow stress (greater than 50000 psi) with the Niblett and Wilks peak being the predominant feature of the damping spectrum at the higher-flow stresses (greater than 30 000 psi). Moreover, the present results in Ni show such similarity to results obtained on deformation-induced peaks in bcc metals that, if the definition of the Bordoni peak given by Niblett and Wilks is broadened to include Ni, then' the peaks in bcc metals can also be included under the definition. Arguments are presented to show that the Bordoni relaxation is best described by the Seeger-Pare hypothesis.

The Bordoni internal friction peak in silver single crystals

“…However, Mecs and Nowick (1968) found that, for a silver single crystal of (1 11) orientation, the peak after a deformation of only 0.5 % was very broad and occurred at a temperature some 20 degrees higher than when the deformation was increased to 5.4 %. This agrees very closely with the behaviour we observed for copper, and even larger temperature shifts have been reported for nickel by Sommer and Beshers (1966) and Venkatesan and Beshers (1970). For each metal the peak occurs at a relatively high temperature for small prior stresses, and its temperature falls with increasing deformation ; in some cases the temperature of the peak begins to rise again for high deformations.…”

The Bordoni internal friction peak in copper

“…Further deformation to 21 % caused the peak to increase in height and moved it to a slightly higher temperature. These effects are in qualitative agreement with the work of Sommer and Beshers (1966) the magnitudes of the changes in the temperature of the peak appear to be much smaller for copper.…”

“…In particular, the peak is usually considerably broader than that calculated for a single relaxation process, and its temperature has been found to depend to some extent on the amount of prior deformation and on the impurity content of the specimen. Such changes in the temperature of the peak are usually only a few degrees, but Sommer and Beshers (1966) and Venkatesan and Beshers (1970) have observed considerably larger variations for nickel when the amount of cold work was changed. Seeger's original theory has been modified by Part (1961), by Seeger andSchiller (1962, 1966), by Alefeld (1967), and by Engelke (1969aEngelke ( ,b, 1970).…”

Anelastic Relaxation in Crystalline Solids

“…The extent to which the experimental results eliminate certain categories of mechanisms will also be mentioned, in preparation for the detailed discussion of mechanisms in Section 13.2. That the Bordoni peak is general to all fee metals is shown by the fact that it has been observed not only in copper and aluminum, on which the most detailed studies have been made, but also in silver, gold, palla dium, and platinum (Bordoni, et al, 1960;Okuda, 1963a,b), as well as in lead (Welber and Quimby, 1958), and nickel (Sommer and Beshers, 1966).…”