Chung, Tsai FuTsai FuChungYeh, Ching WenChing WenYehLiaw, Yow ShiuanYow ShiuanLiawLin, Jia RuiJia RuiLinHo, Ping LuenPing LuenHoHsiao, Chien NanChien NanHsiaoTsao, Cheng SiCheng SiTsaoChou, Che MinChe MinChouYang, Yo LunYo LunYangJER-REN YANGChen, Chih YuanChih YuanChenHong, WayneWayneHong2023-10-252023-10-252023-12-1509258388https://scholars.lib.ntu.edu.tw/handle/123456789/636523A study on the deformation behavior with increase in strain during upsetting-extrusion (UE) was studied (i.e., No-UE, Small-UE, and Large-UE strains) at 350 °C in Al-8.9Zn-2.2Mg-2.1Cu-0.14Zr-0.02Sc (wt%) alloys to evaluate the strengthening effects of grain size/texture and co-precipitation for different ageing (i.e., as-received, T4, and T6 aging) conditions. In as-received samples, electron back-scattered diffraction observations revealed that increasing UE strain enhances the formation of continuous and discontinuous dynamic recrystallization grains. This reduces the size difference between fine and coarse grains in bimodal structure and produces stronger copper/cubic texture. In small angle X-ray scattering (SAXS), a large UE strain brings about more fraction of Y-phase and GP zones. In T4 Large-UE samples, SAXS indicated higher size stability of disk-like Y-phase. High-angle annular dark field scanning transmission electron microscopy images revealed five-layered atomic arrangement of a unit cell of Y-phase, where the center layer was composed of Al and sandwiched layers, 2Cu/2Zn/2Cu and Al/ZnCu/ZnCu/Al. In T6 Large-UE samples, it was observed that the growth of Y-phase is accompanied by intrinsic atomic shift along the [101̅0]Y-phase direction. Furthermore, SAXS quantitatively showed size evolution of η'/η precipitates and formation of a higher aspect ratio of Y-phase. The collective effects of finer bimodal grain structure, stronger fiber texture, and co-precipitation of Y-phase and η'/η precipitates provide evidence higher ultimate tensile strength (∼766 ± 5 MPa) and superior strain (∼10.9 ± 0.4) of large-UE strain samples under T6 ageing.Atomic high-angle annular dark field scanning transmission electron microscopy | Co-precipitation strengthening | High-Zn containing aluminium alloys | Small angle X-ray scattering | Upsetting-extrusion deformations | Y-phase precipitates[SDGs]SDG12journal article10.1016/j.jallcom.2023.1718712-s2.0-85171662988https://api.elsevier.com/content/abstract/scopus_id/85171662988