Internal friction and dislocation collective pinning in disordered quenched solid solutions

Abstract

We introduce the collective pinning of dislocations in disordered quenched solid solutions and calculate the macroscopic mechanical response to a small dc or ac applied stress. This work is a generalization of the Granato–Lücke string model, able to describe self-consistently short and long range dislocation motion. Under dc applied stress the long distance dislocation creep has at the microscopic level avalanche features, which result in a macroscopic nonlinear “glassy” velocity-stress characteristic. Under ac conditions the model predicts, in addition to the anelastic internal friction relaxation in the high frequency regime, a linear internal friction background which remains amplitude-independent down to a crossover frequency to a strongly nonlinear internal friction regime.