Internal friction peaks in a commercial duralloy

M.T. MALACHEVSKY; A. GHILARDUCCI DE SALVA

Journal de Physique Colloques

Société française de physique, EDP Sciences

Lugar: Paris; Año: 1987 vol. 8 p. 435 - 440

0449-1947

The commercial duralloy Al 2024 of composition A1-4.5 wt% Cu-1.5 wt% Mg-0.6 wt% Mn - 4 1 wt% impurities (Si,Fe) waS studied by internal friction at low frequencies.The commercial state "C" was submitted to different thermal and/or mechanical treatments and neutron or electron irradiations to prepare the various samples. The "C" state presented two kinds of peaks: some cold work peaks a t 1 Hz below and near room temperature and a precipitates - dislocations interaction peak a t 244OC (24Hz) with activation energy of 0.94 eV. The presence of dislocations or precipitates alone in the sample leads to the absence of appreciable peaks. At about 200°C the increase of the high temperature background follows an exponential law similar to other Al alloys . The supersaturated solid solution "SSS" state presented a double Zener type peak that can be considered as a contribution of both solutes : Cu and Si. The high temperature background is also present , but a little lower than in the "C" state . By comparing the backgrounds of all the samples we arrive a t the conclusion that its origin is dislocation motion.