@article{CHENG2026, 
author = {Cheng CHENG and Ying XIA and Wancheng LYU and Yizhou SHEN and Wei WANG and Zexing ZHOU and Gui WEI and Xunzhong GUO},
title = {Insights into dislocation and substructure development of 7075 alloy manufactured by additive friction stir deposition in post-dynamic stage: Role of precipitates},
year = {2026},
journal = {Chinese Journal of Aeronautics},
volume = {39},
number = {7},
keywords = {Additive friction stir deposition, 7075 aluminum, Dislocation density, Dislocation evolution, Precipitate, Substructure development},
url = {https://www.sciopen.com/article/10.1016/j.cja.2026.104116},
doi = {10.1016/j.cja.2026.104116},
abstract = {Additive Friction Stir Deposition (AFSD) has emerged as a promising solid-state technique for manufacturing large-scale 7XXX series aluminum components, offering refined microstructures with minimal solidification defects. However, the interplay between precipitate evolution and dislocation/substructure dynamics during multilayer deposition, particularly in the post-dynamic stage, remains inadequately understood. This study systematically investigates the microstructural evolution of AFSD-processed 7075 aluminum alloy through multiscale characterization of dislocation density, precipitate distribution, and substructure morphology. Key findings reveal that η/η′ phases partially dissolve during the dynamic stage, forming Grain Boundary Precipitates (GBPs) and Intragranular Clusters (IPCs), which stabilize grain boundaries while retaining substructures. Subsequent cooling within the η/η′ precipitation window triggers GBPs/IPCs dissolution and static recovery, enhancing grain boundary mobility and reducing dislocation density. Post-dynamic cooling further homogenizes GBPs/IPCs, enabling nucleation of new precipitates (η′, η, Al2Cu) that generate interfacial dislocations to accommodate lattice mismatch. These interactions, coupled with insufficient thermal activation energy, stabilize dislocation networks and substructures (e.g., dislocation loops, low-angle boundaries) within recrystallized grains, ultimately triggering their transformation into substructured grains. Crucially, the inherent thermal cycling in AFSD induces heterogeneous microstructures, highlighting the necessity of location-specific heat treatments tailored to GBPs/IPCs distributions to ensure uniform post-processing.}
}