Grain boundary misorientation dependence of β phase precipitation in an Al–Mg alloy

  Precipitation of β phase (Al3Mg2) in an Al–Mg alloy is investigated by in situ heating and precession diffraction-based orientation imaging in a transmission electron microscope. Initial β formation occurs more readily at low-angle grain boundaries than at high-angle boundaries; however, larger precipitates are found at high-angle boundaries. We propose a mechanism for β formation based on boundary energy and grain boundary free volume. These results advance the understanding of β phase formation, aiding future corrosion prevention.