Accurately measured precipitate–matrix misfit in an Al–Mg–Si alloy by electron microscopy

Abstract

The age-hardenable Al–Mg–Si alloy system is strengthened by needle-shaped coherent β″ phase precipitates. Using distortion-corrected high-resolution scanning transmission electron microscopy images, we measure the considerable misfit between β″ particles and the Al matrix. The β″ phase is found to adapt its lattice parameters to the particle shape, distributing the strain in the Al matrix evenly in its cross-sectional plane. The measured misfits give a good match to reported atomistic simulations for a β″ phase with composition Mg5Al2Si4.