Precipitation sequence of Al₂O₃/Al-Cu-Mg and Al-Mg-Si composite materials

Precipitation sequence of the Al₂O₃/Al-Cu-Mg and Al-Mg-Si composite materials were investigated by high resolution transmission electron microscope (HRTEM) and differential scanning calorimeter (DSC). Precipitation sequence of the Al₂O₃/Al-Cu-Mg composite material changed from that of Al-Cu-Mg alloy (GPB zone→ S') to that of Al-Cu alloy (GP zone → θ) based on results by HRTEM observation. Precipitation sequence of the Al₂O₃/Al-Mg-Si composite material was similar to that of an Al-Mg₂Si alloy including Si in excess (excess Si alloy). A DSC curve of an Al₂O₃/Al-Mg-Si composite material was not in agreement with that of an Al-Mg₂Si alloy. Major peaks in DSC curve of this composite were not clear and this behavior was similar to that of an excess Si alloy including lower Mg₂Si contents rather than a quasibinary Al-Mg₂Si alloy.