Experimental study of the nonlinear internal friction peaks in Al-Mg solid solutions

摘要

Nonlinear internal friction peaks associated with the interaction between dislocations and point defects are experimentally studied in cold-worked Al-Mg solid solutions. It is found that the appearance of these peaks is very sensitive to the cold-work methods among which the stretching method in the strain range of several percent is effective for reproducing the peaks. A maximum of the internal friction vs. strain amplitude at a given temperature around the peak is observed. With the forced vibration method and by using a nonlinear fitting program to subtract the background, the activation energies are measured to be 1.3, 1.1 and 0.7 eV respectively, for the three peaks (P_(L1)P'_1, P"_1) in the order of ascending temperature.