On dynamic and static strain ageing in Cu-2at.% Mn polycrystals

Abstract Measurements of the yield points ΔσA on reloading after ageing at various stress levels (obtained by partial unloading of the tensile specimen) have been performed with Cu-2at.% Mn polycrystals at 313K (strain rate 310−5s−1). At these temperatures solute atoms are supposed to increase the effective obstacle strength (intersections of mobile with forest dislocations) by pipe diffusion from the forest to the mobile dislocations during the waiting time for thermal activation. The stress dependence ΔσA ∝ (σ*)1/3, (with the effective stress σ*) expected according to Friedel's equation is observed. This supports the intersection strengthening model and, hence, the pipe diffusion mechanism for static and dynamic strain ageing in the temperature and strain rate regime of this study.

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