Effect of contact solid solution treatment on peak aging of Al-Zn-Mg-Cu alloys

Contact solid solution treatment (CST) can shorten peak aging time and improve precipitation strength of Al-Zn-Mg-Cu alloys. The effects of CST on the secondary phase evolution of Al-Zn-Mg-Cu alloys were studied and the strengthening mechanisms were also quantitatively evaluated. Compared with the peak aging time of 24h for furnace solid solution treatment (FST), only 18h are needed to reach the peak strength after CST. The results revealed that higher solid solubility caused by CST could increase the driving force of precipitation and reduce the formation temperature of eta' phase. Many fine precipitated phases of the aged sample after CST could be obtained and hinder the dislocation movement and strengthen the alloy. (C) 2020 The Authors. Published by Elsevier B.V.