Creep mechanisms in dispersion strengthened materials

The development in our understanding of creep in dispersion-strengthened materials is reviewed in a historical context. The concept of a temperature dependent threshold stress in power-law creep is discussed in a comparative frame with the thermally activated detachment model involving dislocation-particle interaction. The effect of grain size and threshold stress in ODS and RSP aluminum alloys is discussed in terms of experimental data. The results of several aluminum matrix composites are discussed on the premise that creep mechanism changes with interparticle spacing. The precise n-value and the rate-controlling creep mechanism depends on the relative dimensions of interparticle distance as compared to the effective barrier distance, i.e., grain or subgrain size. The current analysis suggests that. the steady state creep behavior of dispersion-strengthened system is better described by a power-law creep equation with a temperature-dependent threshold stress.