Abstract
The internal friction in polycrystalline, super purity aluminum has been measured during and after creep under constant load by the ultrasonic pulse method. The increase of internal friction was found to be independent of frequency in the measured range (2.5 to 12 Mc). The room temperature recovery of internal friction after unloading could be described by the formula: Δα=C1/ (t+C2)C3. Typical values of the constants C2 and C3 are 10 sec. and 0.6, respectively. The experimental results are discussed in terms of the Weertman-Salkovitz theory of low-amplitude internal friction.