Characterisation of Secondary Precipitation in Al-Cu-Mg-Ge(Si) Alloys

This thesis presents a comprehensive characterisation of microstructural evolutions in Al-Cu-Mg-Ge and Al-Cu-Mg-Si alloys, including identifying the crystal structures and compositions of nanoscale precipitates in these alloys at atomic resolution. The secondary precipitations inside primary θ′ precipitates are examined and analysed in detail to improve the understanding of complex solid-state phase transformation during precipitation process in these alloys, that is also of great significance for revealing the precise roles of Ge or Si on precipitation process in aluminium alloys