[SY-C4] Symposium C-4

[SY-C4] Dislocation-precipitate interaction in Al-Mg-Si alloys

^○Inga Gudem Ringdalen¹, Sigurd Wenner¹, Jaime Marian² (1.Dept. of Materials and Nanotechnology, SINTEF, Norway, 2.Dept. of Material Science and Engineering, UCLA, United States of America)

Partial ageing of commercial Al-Mg-Si aluminum results in microstructures characterized by needle-shaped Si/Mg-rich precipitates. These precipitates belong to the non-equilibrium β'' phase and are coherent with the fcc Al lattice, despite of which they can cause considerable hardening. We have investigated the interaction between these β'' precipitates and dislocations using a unique combination of modeling and experimental feedback. Dislocation-precipitate interactions including precipitate stress fields are simulated using discrete dislocation dynamics. The displacement fields due to the precipitates are captured by expressions that satisfy elastic equilibrium and are fitted to high-resolution electron microscopy measurements. The stress fields are derived from the displacements assuming isotropic elasticity, and used to study the strength of individual precipitates to dislocation glide as a function of precipitate size, orientation, and dislocation character and length. The dislocation dynamics results are then used to parameterize a probabilistic analysis model to study the difference between the bulk material and the precipitate free zones along the grain boundaries of these alloys.