  The mechanisms of dislocation/precipitate interaction were studied by means
of discrete dislocation dynamics within a multiscale approach. Simulations were
carried out using the discrete continuous method in combination with a fast
Fourier transform solver to compute the mechanical fields. The original
simulation strategy was modified to include straight dislocation segments by
means of the field dislocation mechanics method and was applied to simulate the
interaction of an edge dislocation with a $\theta'$ precipitate in an Al-Cu
alloy. It was found that the elastic mismatch has a negligible influence on the
dislocation/precipitate interaction in the Al-Cu system. Moreover, the
influence of the precipitate aspect ratio and orientation was reasonably well
captured by the simple Orowan model in the absence of the stress-free
transformation strain. Nevertheless, the introduction of the stress-free
transformation strain led to dramatic changes in the dislocation/precipitate
interaction and in the critical resolved shear stress to overcome the
precipitate, particularly in the case of precipitates with small aspect ratio.
The new multiscale approach to study the dislocation/precipitate interactions
opens the possibility to obtain quantitative estimations of the strengthening
provided by precipitates in metallic alloys taking into account the
microstructural details.
