The reconstruction of segmental bone defects requires patient-specific scaffolds that combine mechanical safety, biological functionality, and rapid manufacturing. We converted CT-derived mandibular geometry into a functionally graded Ti-6Al-4V lattice and optimised porosity, screw layout, and strut thickness through a cyber-physical loop that joins high-fidelity FEM, millisecond ANN, and a BN for uncertainty quantification. Fifteen candidate scaffolds were fabricated by direct metal laser sintering and hot isostatic pressing and were mechanically tested. FEM predicted stress and stiffness with 98% accuracy; the ANN reproduced these outputs with 94% fidelity while evaluating 10,000 designs in real time, and the BN limited failure probability to <3% under worst-case loads. The selected 55–65% porosity design reduced titanium use by 15%, shortened development time by 25% and raised multi-objective optimisation efficiency by 20% relative to a solid-plate baseline, while resisting a 600 N bite with a peak von Mises stress of 225 MPa and micromotion < 150 µm. Integrating physics-based simulation, AI speed, and probabilistic rigour yields a validated, additively manufactured scaffold that meets surgical timelines and biomechanical requirements, offering a transferable blueprint for functional scaffolds in bone and joint surgery.
Porous Ti-6Al-4V lattice implants combine high specific strength, osseointegrative porosity, and compatibility with additive manufacturing, but conventional stiffness tuning through porosity, pore size, or unit-cell topology compromises biological pore requirements. This study presents a computational design framework in which structural kurtosis, the normalized interlayer offset between neighboring layers of a periodic cubic lattice, regulates elastic response at fixed global porosity. Closed-form expressions for the effective modulus are derived from first principles: the aligned configuration from the axial load-bearing area fraction, and the interlayer-shifted configuration from Euler–Bernoulli beam theory for guided-end connecting members. The derivations reproduce the Gibson–Ashby exponents n = 1 and n = 2, replacing the previously asserted power law, and a calibrated one-parameter interpolation bridges intermediate offsets. At 65% porosity, the effective modulus falls from 16.5 GPa in the aligned lattice to 2.64 GPa in the shifted lattice. A local-yield analysis based on peak bending curvature gives recoverable elastic strains of 1.37% at 89% porosity and 0.68% at 65%; the compliance-based values of 20.5% and 5.12% are kinematic upper bounds that neglect plastic hinging. A prefactor-free benchmark shows that obtaining the same 6.25-fold reduction by increased porosity alone would require 85.9–94.4% porosity and 0.17–0.28 mm struts, outside the osseointegration window and the resolution of selective laser melting. A GAN-CAD-FEA workflow reproduced the analytical moduli to within 7% across six design cases. All results are analytical and numerical; no specimens were fabricated or tested, and experimental validation remains required.
Peri-implant acidification during inflammation can break down the passive film of titanium implants and release Ti, Al and, in particular, V from Ti-6Al-4V. This study aimed to identify an air thermal-oxidation regime that makes the Ti-6Al-4V surface resistant to a severe acid challenge. Polished discs oxidised at 150–800 °C for 15–60 min were characterised by optical metallography, XRD and SEM/EDS and tested for 240 h in 30% HCl, with ICP-MS analysis of the spent solutions. Protection depended strongly and non-monotonically on the temperature–time combination. Oxidation at 150 °C produced only Ti2O and slightly reduced the resistance. At 650 °C for 30 min, an ordered Ti6O layer (30.0 wt.%) with incipient rutile (1.3 wt.%) formed, the mass loss fell below the gravimetric detection limit, and dissolved Ti, Al and V decreased from 674, 52 and 32 mg L−1 to 1, 1.5 and 0.29 mg L−1. At 750 °C, the rutile content increased to about 20 wt.%, but the boundary oxide network broke up into Al- and V-rich islands and only 15–18% protection was retained. Protection was therefore governed by the continuity and chemical uniformity of the oxide layer rather than by the amount of rutile formed. These accelerated-test results require confirmation in simulated body fluids and biological studies.
29 December 2023 in Powder Metallurgy аnd Functional Coatings
Experimental and analytical studies on gas atomization of the molten beryllium and the production of beryllium granules are presented. The impact of various factors, including the choice of gas (nitrogen or helium), the cooling gas flow rate (ranging from 300 to 650 m/s), melt temperature, and droplet size (<500 µm), on the cooling rate and granule properties, is demonstrated. It has been determined that the solidification of beryllium granules can occur through two distinct mechanisms depending on the atomization process. These mechanisms include crystallization and amorphization (glass transition). When beryllium melt is atomized with nitrogen, granules with diameters less than 100 µm solidify via the amorphization mechanism (glass transition), while those with diameters exceeding 300 µm solidify through crystallization. In such cases, a portion of granules with sizes ranging from 100 to 300 µm undergoes a mixed mechanism solidification. In this process, the surface becomes amorphous, while the central part crystallizes, resulting in the formation of a “shell” on the surface, marking the transition from the glass transition mechanism to the crystallization mechanism. The thickness of this “shell” depends on the granule diameter, measuring 10–15 µm for 300 µm granules and 20–25 µm for 100 µm granules. The findings from this research align well with the hypothesis of a glass-crystalline mechanism of beryllium granule solidification, which leads to their separation at the interfacial boundary. Such solidification through a mixed mechanism results in the creation of a removable “crust” on the granule, which is typically more contaminated with impurities. Understanding this effect opens up possibilities for practical applications in the production of specialized materials from beryllium. The ability to separate the “crust” from the “core” provides the conditions for obtaining specialized sintered beryllium grades suitable for use in nuclear reactors and foil production, where a beryllium microstructure with “clean” boundaries is essential.
15 April 2024 in Powder Metallurgy аnd Functional Coatings
The paper presents the results of theoretical and experimental studies regarding the quality of diffusion welding of the beryllium–copper composite. Numerical investigations of the parameters of heterodiffusion of diffusants and the thickness of the Be–Cu pair welded joint under varying temperature-time conditions were conducted. The analytical examinations revealed that the thickness of the diffusion weld at the Be–Cu joint varies between 26 and 345 µm, with the temperature increasing from 800 to 1000 °C and the holding time ranging from 20 to 120 min. The calculated layer thickness during the diffusion welding of a Be–Cu pair at 800 °C for 2 h is 65 µm, with 15 µm on the beryllium side and 50 µm on the copper side. Notably, a CuBe3 intermetallic compound zone can form in the diffusion weld, which should be considered an adverse factor that reduces the mechanical properties. To theoretically substantiate the modification of the structure and properties of the diffusion zone, a numerical study of welding was carried out using a 10 μm thick nickel foil spacer, which is readily soluble in beryllium. It was demonstrated that after exposure to temperature-time conditions at 900 °C for 20 min, a 50 µm wide diffusion-bonded joint is formed. Its structure includes two single-phase zones of solid solutions based on copper and beryllium, as well as two two-phase regions consisting of solid solutions hardened with intermetallic compounds. Since the weld lacks structural zones consisting solely of intermetallic compounds (unlike when welding the Be–Cu diffusion pair), there are grounds to anticipate a reduction in the embrittling effect on the weld. The results obtained from the analytical studies can serve as the foundation for a theoretical prediction method for assessing the quality of diffusion welding of the beryllium–copper composite.
30 September 2026 in Science and Technology of Kazakhstan
This paper presents the results of statistical studies on the quality stabilization of beryllium semi-finished products obtained by vacuum hot pressing. The quality of hot-pressed products, as regulated by technical specifications, is primarily characterized by impurity content and physical-mechanical properties. The main unstable parameter is the ultimate tensile strength. The article examines the causes of instability in the strength characteristics of technical-grade beryllium produced by powder metallurgy under industrial manufacturing conditions. Correlation analysis revealed the primary factors determining the quality of beryllium in terms of its mechanical properties. It is shown that the silicon impurity exerts a softening effect on hot-pressed beryllium. An increase in silicon content from 0.01–0.02 % to 0.02–0.03 % leads to a decrease in average tensile strength values from 377 to 357 MPa and increases the rejection rate from 6 % to 40 %. The authors propose a mathematical model for predicting the strength properties of sintered beryllium, derived through regression analysis, which accounts for the combined influence of the chemical and physical characteristics of the powders, as well as the consolidation parameters. The model enables the determination of optimal pressing parameters, ensuring stable quality of the finished products and, consequently, a reduction in the production rejection rate. Keywords: Technical-grade beryllium, powder metallurgy, vacuum hot pressing, tensile strength, correlation and regression analysis.