Precipitation of dispersoids in Al–Mg–Si alloys with Cu addition

Abstract

Nanoscale α-Al(FeMn)Si dispersoids in Al alloys play a vital role in improving the recrystallization resistance and mechanical properties of alloys at elevated temperatures. This study investigates the influence of Cu on the precipitation behavior of α-dispersoids in Al–Mg–Si alloys during heat treatment at 500 °C. α-dispersoids in an alloy without Cu addition had rod- or plate-like morphologies. The addition of Cu effectively inhibits the precipitation of α-dispersoids through the formation of fine spherical dispersoids, resulting enhanced mechanical properties of the alloy at elevated temperatures. Evidence from high-resolution transmission electron microscopy demonstrated that the rod- or plate-like structures have simple cubic structures, whereas the spherical α-dispersoids are coherent with the Al matrix along the [101] zone axis of Al, resulting in finer dispersoids, higher thermal stability, and lower coarsening rates. However, its crystal structure requires further investigation.