In this work, nanocrystalline AZ31 magnesium alloy powders, reinforced by submicron TiB₂ particles, were prepared via mechanical milling. It was found that TiB₂ particles stimulated the fracture and welding of AZ31/TiB₂ powders, leading to the acceleration of the milling process. Meanwhile, the TiB₂ particles were refined to submicron-scale size during the milling process, and their distribution was uniform in the Mg matrix. In addition, the matrix was significantly refined during the milling process, which was also accelerated by the TiB₂ particles. The formation of grain boundary segregation layers also led to the weakened TiB₂ peaks in the XRD patterns during the mechanical milling. The grain sizes of AZ31–2.5 wt % TiB₂, AZ31–5 wt % TiB₂ and AZ31–10 wt % TiB₂ powders were refined to 53 nm, 37 nm and 23 nm, respectively, after milling for 110 h. Under the combined effect of the nanocrystalline matrix and the well-dispersed submicron TiB₂ particles, the AZ31/TiB₂ composites exhibited excellent micro-hardness. For the AZ31–10 wt % TiB₂ composite, the micro-hardness was enhanced to 153 HV0.5.

As an important artificial implant material, the corrosion resistance of NiTi shape memory alloy is closely related to the machined surface quality. In this paper, the multiple analysis methods concerning potentiodynamic polarization, impedance spectrum and corrosion morphology are used to analyze the corrosion resistance of the alloy. The potentiodynamic polarization and impedance spectrum test results show that the conductivity and corrosion current density of electrochemical polishing surface decrease, and the polarization resistance and corrosion potential increase compared with milling. After electrochemical polishing, the surface roughness of the milling sample is decreased, and the NiTi alloy of austenite phase is transformed into TiO₂, which improves the corrosion resistance of the alloy. In addition, there are pitting corrosion, hole corrosion and crevice corrosion morphology on the milling surface, while the pitting corrosion and hole corrosion exist on the electrochemical polishing surface. The corrosion morphology verified the analysis of potentiodynamic polarization and impedance spectrum. The multiple analysis method proposed in this paper can be used as a more accurate evaluation method for the corrosion resistance of alloy surface, avoiding the error of analysis results caused by the impedance spectrum equivalent circuit and potentiodynamic polarization following Tafel relationship.

Fabricating micro-textures with specific parameters (size, shape, and distribution) on the surface of mechanical components has the potential to improve the tribological performance. When the ultrasonic vibration is applied to depth direction of turning, the micro-textured surfaces with specific dimples can be generated in a simple and effective way. Under the intermittent cutting condition, the generation mechanism of the micro-textured surface, processed by this one-dimensional ultrasonic vibration-assisted turning (1D UVAT), was further carried out. A novel theoretical model was firstly proposed from the perspective of geometric kinematics, which can reveal the influence of three intersection states between the flank face and cutting trace (η₁ < tan α, η₁ > tan α > η₂ and η₂ > tan α) on the size, shape, and distribution of micro-dimples, generated under intermittent cutting conditions. Then, a simulation model was built to predict the surface topography and dimple profile under different processing parameters. The results show that the processing parameters, including clearance angle, spindle speed, and vibration amplitude, have an important influence on the intersection state. By choosing the proper clearance angle, spindle speed, or vibration amplitude, the different intersection states can be realized, and the corresponding size, shape, and distribution of micro-dimples will be changed accordingly. With the increase of the nose radius and feed rate, the dimple width and distance between adjacent dimples along feed direction can both increase accordingly. The simulation results not only confirm the feasibility of the proposed theoretical model, but also show that the discrete or continuous micro-dimples, with different sizes and specific shapes, can be controllably generated on cylindrical surface by 1D UVAT under intermittent cutting conditions.

A systematic investigation was conducted on the laser shock forming (LSF) process of carbon steel Q355ME sheets and practical skin components, focusing on the influence of absorption layer types, laser energy, and impact cycles on forming capacity and surface properties. Three kinds of absorbing layers were compared in the experiment: no absorbing layer, 0.1 mm aluminum foil and 0.12 mm black tape. The results show that when the black tape is used as the absorbing layer, the forming effect is the best, the arc height value reaches 2.63 mm, and the radius of curvature is 1066 mm. Using 0.1 mm thick black tape as the absorption layer and laser parameters of 10% overlap rate, 15 ns pulse width, 4 mm spot, and 1064 nm wavelength, the single impact of 13 J, 15 J, and 17 J, and one, two, and three impacts of 15 J energy were carried out on the plate. It was found that the increase in laser energy and impact times resulted in increases in deformation, surface roughness, microhardness, and residual stress of the plate. The surface work hardening phenomenon of Q355ME plate after laser shock slowed down the increase in these performance parameters. The experimental results show that the laser energy is linearly positively correlated with the residual stress in a certain energy range. Under the optimized laser process parameters, the forming error of the actual skin parts is controlled within ± 0.4 mm, the surface residual stress increases by 368.9%, and the surface microhardness increases by 10.4%. The ultra-high strain plastic deformation and grain refinement on the surface of the sheet were caused by multiple laser shock peenings, which confirmed that LSF technology can improve the formability of carbon steel skin parts and improve its surface properties.

The mechanical properties of continuous-fiber-reinforced composites in FDM-3D printing are significantly influenced by process parameters. However, research in this area is constrained by printing equipment, control software, and material preparation. This study examines how the tensile and interlaminar shear properties of CCF/PA and CF/PEEK are affected by continuous-fiber nozzle temperature, platform temperature, and printing speed. Studies indicate that enhancing the nozzle temperature can notably improve mechanical properties by enhancing material flowability, ensuring consistent fiber encapsulation and reducing pore defects. Increasing the platform temperature initially boosts both tensile strength and ILSS, but, beyond a certain point, these properties decline. Inadequate platform temperature can result in uneven infiltration and diffusion among deposited CCF/PA paths, leading to void defects. Conversely, excessive platform temperature can cause semi-molten CCF/PA layers to be vulnerable to nozzle pressure and scraping, resulting in continuous-fiber debonding and interlayer tearing. Furthermore, lower printing speeds extend the melt wetting time between adjacent paths, promoting diffusion and adhesion for enhanced performance. Following an experimental investigation, the optimal parameters are identified as a nozzle temperature of 295 °C, a platform temperature of 240 °C, and a printing speed of 3 mm/s. This research provides valuable guidance for the practical production of continuous-fiber-reinforced composites using FDM-3D printing.