Zheng Xiang

Laser powder bed fusion (LPBF) provides an effective method for the preparation of self-sealing powder damping components, but the introduction of cavities simultaneously leads to a decrease in the mechanical properties of the components. In order to achieve a synergistic improvement in the stiffness and damping performance of LPBFed self-sealing powder damping components, this paper designed and prepared TC4 alloy beams incorporating both self-sealing powder and lattice structures, characterized by their manufacturing quality, mechanical properties, and damping performance and established corresponding static and dynamic models. The results show that, as the diameter of the lattice struts increases, the stiffness of the self-sealing powder beams incorporating lattice structures increases, while the amplification factor and structural damping ratio decrease, eventually tending toward that of the solid beam. The changes in damping performance are related to the powder volume and the internal surface area. Compared to self-sealing powder beams containing only cavities, self-sealing powder beams incorporating lattice structures with strut diameters of 0.6 mm and 0.9 mm not only exhibit a significant improvement in stiffness but also demonstrate smaller amplification factors and larger structural damping ratios under 1 g and 2 g vibration inputs, achieving a synergistic enhancement of stiffness and damping. This study provides an effective reference for the regulation and optimization of the mechanical properties and damping performance of LPBFed self-sealing powder structures.

Laser powder bed fusion (LPBF) technology offers an effective approach for fabricating high-performance superelastic NiTi alloys. This study achieved Ni_51.9Ti_48.1 alloys with outstanding superelastic properties through a triple optimization design of the initial powder composition, printing process parameters, and post-processing. The phase transformation behavior and microstructure of the alloys were systematically investigated. The results indicate that as energy density increases, the size and quantity of pore defects in LPBF-fabricated Ni_51.9Ti_48.1 alloys increase, phase transformation temperatures rise, and hardness conversely decreases. Ni_51.9Ti_48.1 alloys produced at lower energy densities exhibit fewer dislocations. After annealing at 600 °C, Ni₄Ti₃ and R phases form internally, resulting in a maximum superelasticity of 6.64%. Conversely, Ni_51.9Ti_48.1 alloys produced at higher energy densities exhibited a large number of dislocations and formed subgrains after annealing at 600 °C. Additionally, due to the high void volume fraction, they demonstrated deteriorated superelasticity.

Laser powder bed fusion (LPBF) presents both opportunities and challenges with regard to the customisation of NiTi alloy properties. This paper presents a systematic study of the influence of process parameters on the superelasticity of LPBF Ni-rich Ni_51.3Ti_48.7 shape memory alloy. The findings demonstrate that NiTi alloys produced through disparate process parameters exhibit disparate phase transformation behaviours and microstructures, which in turn result in varying degrees of superelasticity. At an energy density of 166.7 to 233.3 J/mm³, LPBFed Ni-rich Ni_51.3Ti_48.7 is predominantly in the martensite phase at room temperature due to the high phase transition temperature caused by a large amount of Ni evaporation loss, and exhibits almost no superelasticity. At an energy density of 66.7 to 116.7 J/mm³, LPBFed Ni-rich Ni_51.3Ti_48.7 has less Ni evaporation loss and lower phase transition temperature. It is primarily austenite phase at room temperature, and contains nano-precipitated phases internally, thereby exhibiting excellent superelasticity. The recovery rate is in excess of 5.5% at the initial compression (up to 5.7%) and in excess of 5.0% following ten cycles (up to 5.3%). Furthermore, the lower the energy density, the smaller the stress–strain hysteresis of LPBFed Ni-rich Ni_51.3Ti_48.7, with a variation range of 1.8–3.9 mJ/mm³.