The unique hybrid precipitate in a peak-aged Al-Cu-Mg-Ag alloy

The prevalent hardening phase forming in an Al-Cu-Mg-Ag alloy after peak-aging at 150 and 190 degrees C has been investigated using transmission electron microscopy methods. The precipitate atomic structure was determined. It is a hybrid precipitate (HP) with plate morphology on {111} Al planes, consisting of orthorhombic and hexagonal structural fragments. Density functional theory calculations suggest that the hybridization reduces structural incompatibility of the HP plates with the Al matrix at the broad interfacial boundaries. Incorporation of Cu, Mg and Ag in the bulk HP structure reduces its formation enthalpy. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

Research on the prevalent hardening phase forming in an Al-Cu-Mg-Ag alloy after peak-aging at 150 and 190 degrees C using transmission electron microscopy methods revealed a hybrid precipitate with plate morphology on {111} Al planes, consisting of orthorhombic and hexagonal structural fragments. Density functional theory calculations suggested that hybridization reduces structural incompatibility of the plates with the matrix, and the incorporation of Cu, Mg, and Ag in the structure reduces its formation enthalpy.