Creep in dispersion strengthened aluminium alloys at high temperature : a model based approach

Abstract

The mechanism of dispersion strengthening has been studied in dispersion-strengthened aluminium alloys produced by reaction milling. The beneficial effect of second phase particles is usually attributed to the existence of a "Threshold stress", below which particles cannot be surmounted by climbing dislocations. But, as well be shown below, predictions of this "threshold stress" concept are widely inconsistend with the experimentally observed creep behaviour. A new constitutive equation is proposed which is based on TEM observations suggesting thermally activated dislocation detachment from the particles to be rate controlling. Creep in several dispersion-strengthened alloys can be consistently described with this concept, which also points to ways of optimizing these alloys.