Ultrasonic attenuation study of defects in aluminium under the action of constant stress

Abstract

In attempting to distinguish the interaction between dislocations and that between dislocations and point defects, the variations of the ultrasonic attenuation, Δα, and strain ɛ are measured as a function of action timet of different constant tensile stress for 99.999 Al polycrystalline specimens at room temperature. It is found that the ultrasonic attenuation decreases and the strain increases at the beginning, and then reaches a saturation state with increasing time. The Δα can be divided into two parts. The initial decrease in Δα is due to the interaction between dislocations and point defects and the final equilibrium is caused by an interaction purely between dislocations. When the applied constant tensile stress is lower than 0.9 MPa, there is no dislocation multiplication.