Evidence for Dislocation Breakaway in Pure Aluminum

Abstract

Attention is called to the very rapid increase in acoustic attenuation at low strains, and it is pointed out that this effect has been observed only in the highpurity almost single-crystal sample. It is proposed that this rapid attenuation increase at very low strain is an example of dislocation''breakaway'' and that the effect is caused by an increase in dislocation loop length arising when the dislocations free themselves from relatively weak pinning,; at low strains. (A.C.)