Lei Zhao

To investigate short-process additive manufacturing, a single-track ZL102 alloy deposit was fabricated via a self-developed Additive Friction Stir Deposition (AFSD) system. Analysis of its microstructure and mechanical properties elucidated the mechanisms of defect formation and material flow. Research indicates that the deposited layer achieves a tensile strength, yield strength, and elongation of 205.83 MPa, 112.71 MPa, and 37.55%, respectively. These properties demonstrate superior impact resistance compared to both the base material and traditional castings. This study confirms the feasibility of high-efficiency AFSD for ZL102, thereby establishing a crucial process foundation for its application.

The rising industrial demand for ultra-lightweight materials with exceptional strength and toughness has intensified interest in dual-phase Mg-Li alloys due to their low density and high specific strength. While much of the research on Mg-Li alloys has concentrated on conventional strengthening methods, such as grain refinement and solid-solution strengthening, overcoming the challenge of plastic deformation compatibility between the α- and β-phases remains unresolved. This study focuses on Mg-8Li binary alloy, systematically investigating the impact of rolling deformation temperature and strain on the phase structures. A detailed analysis of fracture behavior reveals a novel brittle–tough composite fracture control strategy that enhances both strength and toughness simultaneously. This work advances the understanding of phase structure control and its role in strengthening and toughening mechanisms, offering critical insights for the development of next-generation dual-phase magnesium alloys.

Ducted UAVs have attracted much attention because the duct structure can reduce the propeller tip vortices and thus increase the effective lift area of the lower propeller. This paper investigates the effects of parameters on the aerodynamic characteristics of ducted UAVs, such as co-axial twin propeller configuration and duct structure. The aerodynamic characteristics of the UAV were analyzed using CFD methods, while the impact sensitivity analysis of the simulation data was sorted using the orthogonal test method. The results indicate that, while maintaining overall strength, increasing the propeller spacing by about 0.055 times the duct chord length can increase the lift of the upper propeller by approximately 1.3% faster. Reducing the distance between the propeller and the top surface of the duct by about 0.5 times the duct chord length can increase the lift of the lower propeller by approximately 7.7%. Increasing the chord length of the duct cross-section by about 35.3% can simultaneously make the structure of the duct and the total lift of the drone faster by approximately 150.6% and 15.7%, respectively. This research provides valuable guidance and reference for the subsequent overall design of ducted UAVs.