High-efficient hybrid arc and friction stir additive manufacturing of high-performance Al-Cu-Mg-Ag-Zr alloy: Microstructural evolution and precipitation behaviors with Ω/L1₂ co-precipitates

Cost-effective and convenient additive manufacturing technologies are recognized as suitable alternatives for achieving lightweight aluminum alloy components with dense and defect-free parts toward high mechanical properties. Herein, a high-efficient hybrid arc and friction stir additive manufacturing (HAFS-AM) technique was employed to fabricate a high-performance Al-Cu-Mg-Ag-Zr alloy part. The AC pulsed tungsten inert gas (TIG) was utilized for the rapid pre-deposition of Al-Cu-Mg-Ag-Zr alloy with high efficiency. Friction stir processing contributed to eliminating pore defects and refining coarse microstructure in the pre-deposited arc layers, accounting for enhancing mechanical properties. During the HAFS-AM, the coarse θ phase with continuous network morphology was completely broken and gradually dissolved into the α-Al matrix. The addition of Zr element promoted the precipitation of coherent L1₂-Al₃Zr inducing dislocation shearing behavior. The Mg and Ag additions accelerated the precipitation of semi-coherent plate-like Ω and σ phases, where a critical size (thickness and diameter) of precipitates existed for deciding the behaviors of dislocation shearing and dislocation looping. The ultimate tensile strength and elongation of the HAFS-AMed steady-state layer reached 262 MPa and 18.8 %, which were increased by 21 % and 96 % compared to that of the arc layer, respectively. The combined effect of arc and friction stir with high efficiency achieved high-performance manufactured components, expediting the future industry application of advanced additive manufacturing technology.