Stanislav V. Chernyshikhin

A Ti–6Al–7Nb–0.3Y spherical powder was produced by ultrasonic atomization (UA), and its < 63 µm (d₅₀ ≈ 53 µm) and 63–125 µm (d₅₀ ≈ 82 µm) fractions were characterized for laser powder-bed fusion (LPBF) of patient–specific biomedical implants. Both fractions show near-ideal sphericity (1.01) with no satellites or internal pores, flow times of 26.8–28.0 s/50 g and bulk densities of 2.35–2.45 g/cm³ (51–53% of true density), matching commercial powder-bed feedstocks. XRD revealed only hexagonal α(α′)-Ti with a microstrain of 0.45–0.55%. Nanoindentation showed a hardness of 4.55–4.90 GPa, exceeding that of laser-powder-bed-fused Ti–6Al–4V (3.66 GPa), and an elastic modulus of 119–148 GPa on rigidly supported particles. Simultaneous thermal analysis showed stability up to 450 °C in all atmospheres, oxidation in air above 720 °C (E_a ≈ 160–170 kJ/mol) and mass gains at 1195 °C of 23.2–25.7% (air), 4.9–6.8% (N₂) and 1.7–2.1% (Ar). The Ti–6Al–7Nb–0.3Y powder contains 0.69–0.74 wt.% Oxygen, far beyond the scavenging capacity of the retained 0.11–0.12 wt.% Yttrium, as well as 0.09–0.12 wt.% Nitrogen and 0.013–0.015 wt.% Hydrogen.

Developing specialized aluminum alloys for additive processes is a strategic approach to achieve both strength and mass reduction in high-performance products. The prospects of the new metallic powder composition of Al3Ca2La2Mn0.4Zr alloy for laser powder bed fusion (LPBF) have been studied. It has been found that the best printing mode, providing a more than 99.0% density of the specimens, includes substrate heating to 150 °C and printing with a 350 W laser power, a 1500 mm/s printing speed, a 0.08 mm hatch distance and a 0.03 mm layer thickness (energy density 97.2 J/mm²). The optimal printing mode provides for the following strength parameters: UTS 366 ± 5 MPa, yield strength 223 ± 8 MPa, and relative elongation 30 ± 3%. The alloy exhibits high thermal stability for the structure and its properties. Annealing temperatures below 300 °C have no critical effect on the alloy hardness: the hardness decreases by less than 10% of the initial 110 ± 3 HV. At 350 °C, the hardness decreases by 25.5% (82 ± 2 HV); 100 h exposure at 350 °C reduces the UTS to 265 ± 2 MPa and the yield strength to 178 ± 10 MPa, while maintaining the relative elongation of 29 ± 2%.

The paper analyzes the structure, mechanical and physical properties of orthopedic screws made of 316L medical steel manufactured by laser powder bed fusion (L-PBF). The microstructure and internal defects of the L-PBF samples were examined using a Tescan MIRA LMS scanning electron microscope. The relative density of the printed samples was measured by hydrostatic weighing using an OHAUS electronic analytical balance. The Vickers microhardness of the SLM samples was determined using a Metolab 502 microhardness tester. A WYKO NT1100 non-contact profilometer-profilograph was used to measure the roughness parameters. One of the indicators of 3D printer printing quality is the use of powder with certain characteristics. Before printing, a certification analysis of the powder was performed, which showed that the powder particles were rounded, there were no inclusions, and the size was about 50 μm. It was found that the 3D printing parameters, in particular the laser scanning speed, affect the surface quality (roughness) and the internal structure of the product with areas of different thickness. The results showed that at a low scanning speed, defects (pores) in the massive parts of the L-PBF screw were minimal, and in thin places (thread), the number of defects was higher compared to the massive part. An increase in the laser beam speed leads to an increase in the size and number of defects in the massive part of the product. As for the thin part of the screw (thread), the effect of the laser beam scanning speed on defects was found to be nonlinear: with an increase in the scanning speed, defects first decreased and then sharply increased.

Sustainable feedstock management remains a major challenge in laser beam powder bed fusion (PBF-LB), where conventional reuse strategies are typically limited to sieving and blending rather than full material regeneration. Ultrasonic atomization (UA) offers a fundamentally different powder production route based on capillary-wave instabilities induced at the surface of a molten metal by high-frequency vibrations. In contrast to turbulence-driven atomization, droplet formation in UA is primarily governed by ultrasonic frequency and intrinsic thermophysical properties of the melt, enabling quasi-deterministic particle formation with high sphericity and reduced satellite formation. In this study, ultrasonic atomization was investigated as a closed-loop route for converting PBF-LB-manufactured 316L stainless steel parts into reusable powder. Printed rods were remelted and atomized under controlled variation of electric current and vibration amplitude. The resulting powders were characterized in terms of morphology, internal microstructure, particle size distribution, chemical composition, and gas impurity content. UA produced highly spherical particles with reduced internal porosity and improved flowability compared to the initial gas-atomized powder, while preserving the principal alloying elements. An increase in oxygen content was observed after recycling, attributed to selective high-temperature oxidation under residual oxygen in nominally inert conditions. The results establish a mechanistic framework for transforming consolidated PBF-LB material into secondary feedstock and identify key parameters governing structural and compositional stability in closed-loop recycling.

Over the last decade, laser powder bed fusion (LPBF) received increased attention as a method of producing complex-shaped products from various materials. Recent results indicate the potential of this technology for the production of intermetallic NiTi alloys with shape memory. Several studies have demonstrated a strong influence of the LPBF process conditions on the resulting material properties, i.e., the martensitic phase transformation temperatures, reversible/irreversible strain after cyclic loading, phase composition, chemical composition, etc. However, the mechanisms of functional properties altering during LPBF consolidation remain unexplored in the present state-of-the-art. This study aims to advance the knowledge about tailoring material properties of NiTi under laser influence. In this work, thin-walled samples were manufactured from pre-alloyed NiTi powder via LPBF in a wide window of laser power and scanning speed, excluding hatch spacing by employing a single track-based scanning strategy to reveal the pure effect of the laser’s influence. NiTi samples were characterized by various methods such as differential scanning calorimetry, X-ray diffraction, and mechanical tests. Established relationships between NiTi properties and the LPBF process conditions provide the basis for the development of NiTi production protocols with controlled functional properties.

Laser powder bed fusion (LPBF) is an advanced additive manufacturing method, but its productivity is relatively low, which limits its application. Performance can be increased without hardware modifications by enlarging the powder-layer thickness. However, this approach requires deeper investigation because the probability of defects (keyhole porosity, lack of fusion) rises substantially, and experiments become costly since each thickness value requires a separate LPBF run. High-fidelity simulation under such conditions can reduce the experimental workload. Reliable predictions, however, require numerous thermophysical parameters; reported values are often inconsistent or unavailable, and few studies have quantified their influence on simulation outcomes. A Lattice Boltzmann-based model is adopted to simulate the keyhole melting mode of AlSi10Mg. The effects of laser spot diameter, laser absorptivity, and the temperature dependence of thermal diffusivity and surface tension on the results are investigated. Predicted melt-pool morphologies are compared with cross-sections of experimental single tracks.

In recent years, significant effort was made to make the 3D printing of fully dense rare-earth permanent magnets a reality. Since suitable Nd₂Fe₁₄B-based initial powder material became available, additive manufacturing implementation spread widely, which led to many studies being focused on using this material in 3D printing. This study shows the principal possibilities of the synthesis of Nd-Fe-B magnets by means of the laser powder bed fusion technique; moreover, this study shows significant progress in increasing their magnetic properties. This progress was made possible by different approaches, such as 3D-printing process optimization, the addition of a second phase (a low-melting eutectic) into the initial powder, the tuning of the main phase’s composition, and exploring different scanning strategies. However, the current level of material magnetic properties obtained via laser powder bed fusion is still far from that of magnets produced by using conventional powder metallurgy methods. The present review aims to capture the current state-of-the-art trials and highlight the main challenges.

Binder jetting is the most widely implemented additive technology for the fabrication of sand molds. However, the use of furan binder-jetting technology in the production of molds for vacuum casting is hindered by the thermal destruction of the furan binder accompanied by violent gas emission that occurs during the mold heating process. This investigation explores the potential of using the molds obtained via furan binder jetting 3D printing and further impregnation in colloidal silica binder and sintering. Two distinct sands, proppant and cenosphere, were utilized in the fabrication of the mold components exhibiting different thermal properties. An examination of the structure of the initial sands and samples produced via different impregnation and sintering regimes was conducted via scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffractometry, thermogravimetric analysis, and micro computed tomography. Furthermore, the bending mechanical properties and linear shrinkage of the samples were determined. The experimental findings demonstrated that the specific impregnation and sintering regimes examined in this study yielded sufficient mechanical properties for the casting molds and the structure with cristobalite bridges. The mold assembly, composed of proppant and cenosphere sands-based parts, was produced, and impeller nickel-based superalloy castings were fabricated. The findings of this study demonstrate that the utilization of a furan binder-jetting technique, in conjunction with impregnation in colloidal silica binder, is a promising technology for the manufacture of high-melting-temperature alloy casting.