Is transition-based approach better for interpretation of dislocation creep mechanisms in dispersion-strengthened materials?

Dispersion strengthening is the best way to achieve high creep strength. It is used for almost all high temperature alloys. While the engineering aspects of dispersion-strengthened creep-resistant materials have developed significantly, the fundamental aspects are still not clear. Interpretations of creep mechanisms in dispersion-strengthened materials are frequently debated in literature. For pure metals and alloys, a number of transitions in creep mechanisms have been proposed, experimentally verified and quite well accepted. On the other hand, no theoretical framework has developed for transitions in dislocation creep mechanisms in dispersion-strengthened materials. In this paper, we highlight different experimental trends and microstructural features in dispersion strengthened aluminum alloys and composites. A need for transition-based approach is discussed.