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-induced breakdown spectroscopy (LIBS) is an ideal method for the online elemental analysis of Laser Powder Bed Fusion (LPBF) components due to its in situ and rapid characteristics. However, the inherent surface roughness of LPBF-fabricated parts causes fluctuations in LIBS spectral signals, consequently affecting the accuracy and stability of quantitative analysis. The underlying physical mechanism by which roughness influences spectral signals remains unclear, which restricts the development of relevant spectral correction algorithms. To address this, we prepared alloy steel samples with surface roughness (S_a) ranging from 4.52 to 12.82 µm by adjusting LPBF process parameters and performed LIBS analysis. By analyzing spectral intensity, signal-to-noise ratio (SNR), and relative standard deviation (RSD), we found that the characteristic spectral line intensities of Fe, Cr, Mn, and Ni initially increased and then decreased with increasing roughness, reaching a peak at S_a = 5.61 µm. This peak intensity was 46.4% higher than that of the roughest sample (S_a = 12.82 µm). Plasma temperature and electron density also reached their maximum values at S_a = 5.61 µm (15 790 K and 1.84 × 10¹⁷ cm⁻³ respectively). The observation results of the volume morphology of the ablation plume and the ablation pit both indicate that roughness affects the LIBS signal through a triple coupling effect: low roughness (S_a = 4.52 µm) leads to energy loss due to high reflectivity, while high roughness (S_a ≥ 7.15 µm) weakens ablation efficiency due to an increased ablation threshold and non-uniform energy distribution caused by microstructures. The sample with S_a = 5.61 µm represents an optimal balance between reflectivity and ablation threshold, exhibiting the largest integral of plume area and time (IPAT) and largest volume of ablation pits uniform ablation, which generates stable plasma and, consequently, high-quality spectral signals. This study elucidates the physical mechanism by which roughness influences LIBS spectral signals through a chained pathway of “laser ablation-plasma evolution-spectral response,” laying a theoretical foundation for the development of spectral correction algorithms tailored for complex LPBF surfaces.

Tantalum − tungsten alloys are critical for extreme aerospace applications. However, the oxidation sensitivity and processability limitations associated with conventional manufacturing routes severely constrain the mechanical performance and manufacturability of tantalum−tungsten alloys. This study proposes a new process for fabricating Ta − 12W alloys using “selective laser melting + rolling + inter-pass electrical treatment” (ET − AMR), which achieves a synergistic enhancement of both strength and ductility. First, a substrate with fine grains, high density, complete element diffusion, and no segregation was fabricated using selective laser melting technology. Subsequent multi-pass rolling refined the microstructure and stored substantial deformation energy along the columnar grain growth direction. Inter-pass electrical treatment facilitated dislocation disentanglement, alleviated stress concentration, and induced strain delocalization. The combined effect of rolling and pulsed current effectively repaired internal pores and cracks, reducing the porosity from 0.15% to 0.002% and significantly improving material densification. Specific annealing procedures further enhanced the mechanical properties and grain evolution behavior of the Ta−12W alloy, with the tensile strength increasing by 63% and elongation approximately 3.3 times higher than those of the as-built state, reaching 986 MPa and 14.8%, respectively. After annealing, coarse–fine grain heterostructures and subgrain-recrystallized heterostructures formed, while columnar grains transformed into layered equiaxed grains along the build direction. During plastic deformation, the heterogeneity in grain size and type led to dislocation pile-up, further enhancing heterogeneous deformation-induced strengthening and promoting a synergistic increase in ductility under high strength. This study provides new insights into the high-performance fabrication and development of tantalum−tungsten alloys.

The inherent brittleness and high ductile-to-brittle transition temperature of tungsten-based heavy alloys are primarily due to the poor cohesion of W grain boundaries and insufficient bonding strength at the W/γ phase interface, which limits their reliability and service life in related applications. This study prepared nano-size La ₂ O ₃ and HfC particles reinforced W–(Fe, Co, Ni) alloys via microwave sintering, including the baseline sample S-A (95.5W–2.63Fe–1.12Co–0.75Ni, in wt%), single addition samples S-B (1La ₂ O ₃ ), S-C (1HfC), and mix addition sample S-D (1La ₂ O ₃ –1HfC). The results show that S-C has the highest relative density of 99.2 ± 0.47 %; S-D has the highest Vickers hardness of 414 ± 13.5 HV and tensile strength of 744.1 MPa; S-B has the optimal strain of 5.1 %. La ₂ O ₃ enhances the plasticity and fracture strain of the composites by grain boundary purification, grain refinement, and interface strengthening, inducing a transgranular fracture mode. HfC promotes the formation of composite carbides, achieving dispersion strengthening and dislocation pinning, primarily enhancing hardness and strength, but with limited improvement in toughness. In S-D, the synergistic effect of La ₂ O ₃ and HfC effectively balances the grain boundary pinning and purification, minimizes microporosity, and optimizes phase interface bonding, thus achieving an excellent synergy between strength and toughness, extending the alloy’s application potential in extreme environments.

Lapping is still an efficient and economical way in diamond shaping process, which is important in both industrial and scientific applications. It has been known that the material removal originates from the phase change or amorphization of diamond crystal carbon atoms that are chemically activated by stress, forming a top layer of amorphous carbon atoms. In this paper, the phase change of amorphous carbon atoms undergoing the nanocutting of amorphous layer during diamond lapping process is studied by molecular dynamics (MD) simulation. Two regions, the debris layer and cutting surface underneath, are studied. In the debris layer, the change of sp² carbon atoms is directly affected by impact, while underneath the cutting surface the changes of carbon atoms are almost not affected; the change speed of amorphous carbon atoms is higher than that of pristine crystal ones; the main phase change is transformation of sp³ into sp²; cutting depth to different extent affects the phase changes of sp³ and sp² carbon atoms. Our study expands the understanding of diamond lapping process.

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.