PORTEVIN-LE CHATELIER EFFECT IN ALUMINUM-MAGNESIUM ALLOYS

Abstract

The behavior of repeated yielding at the temperatures below -40 C was well explained by Friedel's relation based on Cottrell's model. From a comparison of this relation with the present results, it was concluded that the activation energy for migration of a vacancy was 0.27 ev in this phenomenon and the solute concentration on dislocations was the reasonable order of magnitude of 1 when the repeated yielding started. Aging treatment largely affected the repeated yielding. When the alloys were aged for four to eight days at 150 C and contained plate-like precipitates,which inhibited most effectively the slip process of dislocations, repeated yielding with a large amplitude appeared at a high level of applied stress.