Abstract
The precipitation sequence in 7xxx (Al-Zn-Mg-(Cu)) aluminiumseries alloys is generally known as SSSS → GP-zones → η′ + η₁₋₁₄→ η-MgZn₂, yet the exact transition from GP-I zones to η′ remains unclear. To address this, in-situ TEM specimens were prepared by PFIB lift-out of suitable grains from electropolished Al disks, transferred onto DENS heating chips. HAADF-STEM and scanning precession electron diffraction (SPED) will be used during in-situ heating experiments to track the precipitation evolution, and specifically to determine the spatial relationship between GP-I dissolution and η′ nucleation. To date, chips have been prepared and are ready for in-situ experiments. HAADF-STEM and SPED characterization has so far only been performed ex-situ.