Berlin 2005 – wissenschaftliches Programm

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M: Metallphysik

M 48: Mechanische Eigenschaften IV

M 48.4: Vortrag

Dienstag, 8. März 2005, 17:15–17:30, TU H111

On the strengthening effect of precipitates with a negative stacking fault energy — •Volker Mohles — Institut für Metallkunde und Metallphysik, RWTH Aachen, 52056 Aachen

Recent atomistic computer simulations (Embedded Atom Method) by Wirth and Shim have revealed that the interaction between a dislocation and a coherent cobalt precipitate in a copper matrix differs strongly from all expectations. In literature, the interaction is described by the size mismatch (coherence stress). But the quoted simulations showed that another effect is at work in addition: while a first partial dislocation moves, it creates a stacking fault in the copper matrix. But inside the particles it actually moves the cobalt atoms near the glide plane to the more favourable hexagonal positions. The second partial cutting through the particle will restore the unfavourable cubic face centred arrangement. This effect can be described by a negative stacking fault energy inside the particles. In the present talk, the impact of this effect on the particle’s strengthening effect is worked out by dislocation dynamics simulations.