On Rösler and Arzt's new model of creep in dispersion strengthened alloys

Abstract

The model of creep in dispersion (non-coherent particle) strengthened alloys assuming thermally activated detachment of dislocations from particles to be the rate controlling process, recently presented by Rösler and Arzt, is correlated with some available creep and structure data for aluminium alloys strengthened by Al 4C 3 and Al 2O 3 particles. It is shown that though the model requires applied stress dependent apparent activation energy of creep, the stress dependence of creep rate can be satisfactorily accounted for even when this activation energy is stress independent, admitting a strong stress dependence of the pre-exponential structure factor, i.e. of the mobile dislocation density. On the other hand, the model is not able to account for the temperature dependence of creep rate if it is significantly stronger than that of the coefficient of lattice diffusion as is usually the case with alloys strengthened by non-coherent particles in which the attractive dislocation/particle interaction can be expected.