Effect of cyclic ageing on the early-stage clustering in Al–Zn–Mg(-Cu) alloys

The Evolution of Precipitates in an Al-Zn-Mg Alloy

“…The one year NA condition contained a dense population of GPI zones. No GPII zones were observed, consistent with our previous works on other AleZneMg alloys in the same condition [4,19,63]. Interestingly, a small population of h 0 precipitates had already formed during NA.…”

“…All the identified particles exhibit an excess atomic density compared to the surrounding matrix (up to 5 times), suggesting the presence of local magnification effects [61,62]. The particle morphological variation observed by Shah et al [63] on the same alloy confirms this hypothesis. This well-known APT artefact strongly modifies the apparent reconstructed particle morphology [64,65].…”

Precipitation, mechanical properties and early slant ductile fracture in cyclic and naturally aged Al-Zn-Mg(-Cu) alloys

“…Consistently with the work in Ref. [25], these additional images provide evidence that the same type of clusters and GP zones are present in the three conditions, mainly GPI zones and smaller clusters. Microstructural investigations with BF-TEM revealed dislocations that are present both in CA and CA + NA 10 days condition, as seen in Fig.…”

“…The estimation of the reconstruction parameters was carried out using the structural information, according to the protocols of Gault et al [24]. The size of clusters is defined based on the Extent z parameter as explained in [25] and the number densities are measured by taking the ratio of the number of clusters identified to the number of atoms in the dataset. This is done by also taking into account detection efficiency of the APT and the average atomic volume.…”

“…To help understand the origin of the strength gained by CA, APT and HRTEM were used to characterize the microstructure. Detailed quantitative microstructural analysis can be found in Ref [25]. Some additional HAADF-STEM images and SADPs from the 7046 alloy in the CA, CA + 10 days and NA 1 year are provided in Appendix B.…”