On the Precipitation of the -Phase {111} Al Plates in the Al-Cu-Mg Alloy

The precipitation of Omega-phase {111}(alpha) plates in the Al-Cu-Mg alloy has been investigated at a Cu/Mg ratio > 10 and low Si content. Unlike Al-Cu-Mg alloys containing Ag, nanoscale plates with an {111}(alpha) habit plane has been found for the first time to precipitate in the alloy according to a heterogeneous mechanism, namely, along low-angle boundaries, dislocation lines, and at the theta'-phase/Al-matrix interphase boundary.