Fabrication of Al-Cu Alloy via Additive Friction Stir Deposition

This study fabricated AA2024-T4 aluminum alloy components using Additive Friction Stir Deposition (AFSD) to systematically investigate the effects of tool rotational speed (100–400 rpm) on the macroscopic morphology, microstructure, and mechanical properties of the deposited layers. The results demonstrate that defect-free, fully dense deposits with good surface quality were successfully achieved across the entire speed range under a constant traverse speed. The deposition zone exhibited a homogeneous, fine equiaxed grain structure with an average grain size of 2.01 μm. As the rotational speed decreased from 400 rpm to 200 rpm, the ultimate tensile strength in the longitudinal direction increased from 340 MPa to 390 MPa, indicating that a moderate reduction in rotational speed enhances both the strength and ductility of AFSD-fabricated AA2024. This research provides the first revelation of the bidirectional material flow behavior and the mechanisms underlying regional property variations in AA2024 during AFSD. Furthermore, the contributions of different strengthening mechanisms were quantified using a multi-mechanism strength model. These findings offer a significant foundation and theoretical support for the solid-state additive manufacturing of high-performance Al-Cu alloy components.