Search Results (3,061)

To address the challenges of procedural complexity, the lack of an integrated heating–forming capability, and poor formability in the hot forming of titanium alloy skin components, an electrically assisted forming (EAF) process is proposed. A Johnson–Cook constitutive model was established to characterize the flow behavior of Ti–6Al–4V alloy under electric-assisted conditions, achieving a correlation coefficient of 0.968 and an average relative error of 7.67%. Forming parameters were investigated through a combined approach of numerical simulation and experimentation. At a current density of 7.59 A/mm², a forming speed of 1 mm/min, and a friction coefficient of 0.1, the maximum springback of the component was 1.04 mm. Compared with isothermal forming, the EAF process reduced the springback by 7.14% and enhanced the ultimate tensile strength by 5.34%. Microstructural characterization revealed that, under pulsed current, the α-phase grains of the material were refined, whereas the β-phase fraction and the average grain size increased, accompanied by a 15.3% reduction in the geometrically necessary dislocation (GND) density. This study validates the process feasibility of electrically assisted forming for thin-walled titanium alloy skin components. Full article

This research work investigates the machinability of WP7V die steel of very high toughness and wear resistance in turning with a TiAlN-coated carbide tool, with the chip reduction coefficient (CRC) serving as a guide for machining performance and energy requirements. The machining parameters, like cutting speed, feed rate, depth of cut, and machining environment, were assessed to find parameter combinations that encourage established cutting and enhanced chip control. The results illustrate that the CRC is strongly influenced by cutting speed, and at a higher cutting speed (210 m/min), the lowest CRC values are obtained. In dry machining, a medium feed rate (0.1 mm/rev) favors chip breaking, and wet machining results in medium-spiral chips. Long, continuous chips with laminar and sheared surfaces are produced at a low cutting speed (70 m/min). The findings suggest that low CRC values are correlated with stable machining behavior and decreased energy utilization. High cutting speed and the suitable selection of feed rates are needed for the efficient machining of WP7V steel. Full article

A large-size ingot (Φ200 mm × 800 mm) with the nominal composition Ti-46Al-8Nb-2.5V (in at.%) was fabricated via triple vacuum consumable electrode arc remelting in this study. XRD, SEM-EDS, TEM, tensile testing, and chemical analysis were employed to examine phase composition, microstructure, mechanical properties, and impurity contents across the height direction of the large-size ingot. Phase composition differences across different positions arose from the solidification path and elemental distributions. The redistribution of major elements during solid–liquid, allotropic and eutectoid transformations contributed to three types of segregation—namely S-segregation, β-segregation, and α-segregation. The maximum deviations in Al, Nb and V content along the height direction of the ingot were 2.05 at.%, 2.24 at.%, and 0.36 at.%, respectively. The bottom position of the ingot exhibited superior tensile properties at both room and elevated temperatures. The average oxygen and nitrogen contents in the ingot were 717 wt. ppm and 183 wt. ppm, respectively. Full article

In powder-based additive manufacturing (AM), thermal exposure during processing can modify powder surface chemistry and promote oxide growth, even under inert atmospheres from residual oxygen contamination. This study investigates the effect of thermal oxidation on the surface chemistry and triboelectric charging behavior of three AM metal alloy powders: AlSi10Mg, 316L stainless steel (SS 316L), and Ti6Al4V. The work examines the evolution of the oxide layer during baking at 100 and 300 °C using triboelectric charging corroborated by X-ray photoelectron spectroscopy (XPS), diffuse-reflectance spectroscopy, and work-function measurements. The results show that heating modifies the surface oxide state of all powders, with changes dependent on the alloy composition and baking temperature. For AlSi10Mg, heating modified the Al₂O₃-rich surface oxide, with changes consistent with increased oxide ordering and γ-Al₂O₃-like characteristics, with the work function increasing from 4.34 ± 0.01 eV in the as-received (AR) condition to 4.92 ± 0.03 eV after baking at 300 °C. The corresponding triboelectric $n$-exponent increased from 0.91 to 1.38. For SS 316L, transformation of Cr(OH)₃ to Cr₂O₃ reduced triboelectric charge accumulation, while the oxygen concentration increased from 49.92 to 54.87 at.% and the work function decreased from 5.74 ± 0.02 to 5.28 ± 0.04 eV after baking at 300 °C. This reflected a drop in the $n$-exponent from 0.82 for AR to 0.73 at 300 °C. For Ti6Al4V, charging variations were associated with titanium oxide evolution and surface modifications consistent with rutile-related titanium oxide characteristics, with the work function increasing from 5.33 ± 0.01 to 5.44 ± 0.03 eV after baking at 300 °C. The corresponding triboelectric $n$-exponent increased from 0.49 to 0.52. Overall, triboelectric charging is a sensitive approach for detecting thermally driven surface oxide modifications in additive manufacturing powders. Full article

Technological development in surface treatment for biomedical implants has advanced rapidly, yet the integration of additive manufacturing with controlled nano topography remains underexplored. This study investigates a novel bioactive kinetic screw (BKS) produced by 3D printing and CNC machining, followed by different anodization treatments: plasma electrolytic oxidation (PEO), hard anodization (HA), and soft anodization for TiO₂ nanotube (TNT) formation. Scanning electron microscopy revealed that PEO created a uniform macro–micro porous surface with pore sizes ranging from 5–15 µm and porosity values of 22.4 ± 3.2%, while HA produced smaller, less homogeneous pores (0.5–2 µm, porosity 10.7 ± 2.6%). TNTs were successfully formed with an average diameter of 80 ± 12 nm, although distribution was non-uniform in screw grooves. Preliminary finite element analysis demonstrated that Ti6Al4V nanotubes (diameter 50 nm, length 500 nm) withstood applied torque with maximum von Mises stress of 1.5 × 10⁻⁸ N/nm² and maximum strain of 3.56, indicating mechanical resilience compatible with early implant loading. The findings demonstrate that the proposed anodization protocols generate distinct hierarchical surface morphologies on BKS implants while preserving implant geometry. These results provide a structural basis for future investigations of biological performance. Full article

The influence of hydrogenation, mechanical milling, and dehydrogenation parameters on the structure and properties of titanium powders produced from titanium sponge via the hydride–dehydride (HDH) process was investigated. The aim of the study was to compare representative HDH processing routes and identify the processing route that provided the most favorable structural characteristics for subsequent mechanical alloying and powder metallurgy applications. Commercially pure Grade 0 titanium sponge was used as the starting material and was subjected to hydrogenation at temperatures ranging from 350 to 650 °C, short-duration mechanical milling in an argon atmosphere, and vacuum dehydrogenation at temperatures between 750 and 950 °C. The resulting powders were characterized using laser particle size analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The results showed that increasing the hydrogenation temperature promoted the formation of the TiH₂ hydride phase and enhanced powder fragmentation during subsequent mechanical milling. XRD analysis demonstrated effective dehydrogenation, as evidenced by the disappearance of detectable TiH₂ reflections and the restoration of the α-titanium phase within the detection limits of the technique. Qualitative SEM observations indicated that the investigated HDH processing routes influenced particle morphology and agglomeration behavior, whereas EDS analysis demonstrated a relatively uniform distribution of the detected elements without revealing detectable contamination within the analyzed regions. Mechanical alloying of the selected powders with aluminum and vanadium showed that, among the investigated processing routes, the H2–M2–D2 condition provided the most favorable combination of particle size distribution, phase composition, morphology, and elemental distribution for the production of a mechanically alloyed Ti–Al–V powder mixture. Full article

To address the strength–ductility trade-off in titanium alloys, a comparative study was conducted on Ti-6Al-4V (TC4) alloys fabricated by laser powder bed fusion (L-PBF) and electron beam powder bed fusion (EB-PBF). The L-PBF specimen primarily consisted of acicular α′ martensite with high residual stress. In contrast, the EB-PBF specimens, owing to a substrate preheating temperature of 740 °C and a reduced cooling rate (10³~10⁵ K/s), exhibited a stable and coarse α + β lamellar structure. Combined with the high oxygen content (0.24 wt.%) that provided solid-solution strengthening, this morphology enabled simultaneous attainment of a yield strength of 1120 ± 12 MPa and an elongation at fracture of 11.1 ± 1.3%. Notably, deformation-induced HCP→FCC phase transformation occurred in EB-PBF alloys, generating a dual-phase HCP/FCC structure that effectively accommodated plastic strain. These results highlight the superior potential of EB-PBF over L-PBF for fabricating titanium alloys with an exceptional strength–ductility synergy. Full article

Contemporary patient-specific subperiosteal implants (SPIs) have re-emerged as digitally planned, additively manufactured solutions for oral and maxillofacial rehabilitation when conventional endosseous implants are limited by severe atrophy, anatomical constraints, or reconstructive defects. Unlike conventional implants, SPIs behave as fixation-based skeletal frameworks whose performance depends on passive fit, screw fixation, anchorage, framework architecture, material properties, manufacturing accuracy, and prosthetic load transfer. This scoping review evaluated the maturity of mechanical design and validation evidence for contemporary SPIs. Following a predefined internal protocol and PRISMA-ScR, MEDLINE/PubMed, Scopus, Web of Science, Embase, and the Cochrane Library were searched from inception to 13 June 2026. Reference-list screening and citation tracking supplemented the electronic search. Two reviewers independently screened records against predefined eligibility criteria. Data were charted using a predefined extraction form and synthesized descriptively by evidence type, engineering domain, validation stage, and translational status. No meta-analysis was undertaken because of methodological heterogeneity, and no formal risk-of-bias grading was applied. Across 65 included records, the evidence was dominated by descriptive technical studies and comparative computational analyses, whereas direct mechanical testing, fatigue assessment, manufacturing verification, and clinical correlation were limited. Finite element analysis was useful for comparing design alternatives and identifying stress concentrations, but models were heterogeneous and often insufficiently validated. Design modifications generally redistributed stress across the implant–prosthesis–bone system rather than reducing it globally. Titanium and Ti6Al4V were the most established framework materials, whereas polymeric, ceramic, and scaffold-assisted strategies remained preliminary. The principal contribution of this review is a cross-domain appraisal of progression from anatomical feasibility and comparative modeling to manufacturing verification, experimental testing, and clinical validation. An evidence map, minimum reporting checklist, and integrated validation pathway are provided to support reproducible device development. Full article

Two design solutions such as modular and mono-block Ti6Al4V porous implants for femoral defect repair were implemented and compared. Static stress analysis on each model was performed via finite element analysis to investigate potential critical elements that might cause system failure under physiological loads. Prior to calculations, a mesh convergence study was realized by varying the minimum element sizes. The entire bone–prosthetic system was modeled, and design optimization was performed. For mono-block implants, a less stressed configuration was found by changing the plate design. Comparison of the maximum Von Mises stress ${\sigma }_{max}$ and equivalent strain ${\epsilon }_{eq}$ between the models allowed for an understanding of the distribution of the loads and identify areas with critical stress concentration. The modular implant appeared to be highly solicited with stress shielding on epiphyses due to enhanced rigidity at the metal/bone interface. Finally, a study of the deformation on cancellous and cortical bone suggested that a more elastic junction with balanced strain delivery to the bone might improve tissue regeneration when using a mono-block implant. Full article

A Fe₅Cu₅V₃₀Ti₃₀Nb₃₀ high-entropy alloy film was designed as a Cr- and Al-free metallic sensing layer for thin-film strain gauges in high-pressure hydrogen environments. CALPHAD calculations predicted a BCC/B2-type phase field, while XRD, EBSD and GIXRD results supported a BCC-type structure without direct confirmation of long-range B2 ordering. Fe₅Cu₅V₃₀Ti₃₀Nb₃₀ films deposited on Si reference substrates at 150 and 300 W retained broad BCC-type diffraction features. The 300 W film showed a more continuous cross-sectional morphology, good metallic conductivity and a comparable nanomechanical response with slightly higher hardness. Device-level tests were then performed using Cr/AlN/Fe₅Cu₅V₃₀Ti₃₀Nb₃₀ TFSGs on 316L stainless-steel substrates. The devices exhibited average absolute apparent zero shifts of 16.08 με in 12 MPa N₂ and 17.79 με in 12 MPa H₂, with an additional H₂-associated apparent response of only 1.71 με. Static tensile tests in 12 MPa H₂ confirmed a linear strain response with a gauge factor of 1.72 ± 0.01. Full article

Melt-pool depth governs interlayer bonding and porosity in laser powder bed fusion and underpins part qualification, yet predicting it reliably remains difficult. Fast conduction models reach useful accuracy only after the absorptivity is fitted to the depths they are meant to predict, and inverse analyses have been used the same way, to recover a calibrated parameter rather than to test the model. Here, the absorptivity is fixed independently instead, a measured coupling for IN718 and, for IN625 and 316L, a published closed-form relation never fitted to the present depths. This converts a moving-source conduction model from an object of calibration into one of validation. The melt boundary is located by root-finding rather than on a grid, so no discretization error enters the diagnosis. Across 231 single tracks, the model reproduces conduction-regime depth and half-width to within a few percent and underpredicts increasingly once keyholing begins. Inverting each measured depth for the absorptivity conduction would require yielding a fitting-free diagnosis: no conduction-regime track demands a non-physical value, and the inferred value converges near 0.38 against inputs of 0.27 to 0.34, whereas every keyhole-classified track demands a value above unity. Because an inferred absorptivity also absorbs unmodeled transport, downward convection was emulated as an anisotropic effective diffusivity; at the enhancement reported for Marangoni flow, no keyhole track becomes explicable. A measured Ti-6Al-4V absorptivity rise of a factor 1.9 supports the mechanism. An enthalpy-indexed correction and data-driven baselines remain alloy-specific, whereas the physics-based model retains its advantage under cross-alloy extrapolation. All findings are for single tracks on bare plates. Full article

Background: Allograft bone remains an attractive option for anterior cervical corpectomy and fusion (ACCF), but its use can be limited by variable graft geometry, insufficient endplate contact, and operator-dependent trimming. This study aimed to develop a titanium end-disc-assisted allograft construct with a standardized cutting and assembly system and to preliminarily evaluate its static mechanical integrity under axial compression, compression-shear, and torsional loading. Methods: The construct consisted of a controlled-length bone graft, two Ti6Al4V end-discs, and four countersunk fixation screws, forming a graft–disc construct with a maximum total height not exceeding 40 mm. The end-discs incorporated angled screw holes, bone-graft filling spaces, and enlarged contact surfaces. A modular preparation system was designed for graft clamping, length definition, guided cutting, alignment, pre-drilling, and screw fixation. Porcine rib specimens were used as an allograft substitute. Native bone and assembled constructs were tested under static compression, compression-shear, and torsion. Results: The system produced standardized constructs. Except for axial compressive stiffness, the assembled constructs showed numerically higher compressive yield force, shear stiffness, shear yield force, torsional stiffness, and yield torque than native bone; however, these findings were interpreted descriptively because of the limited sample size. Failure occurred mainly within the bone, with no obvious failure at the bone–titanium interface, titanium end-discs, or fixation screws. Conclusions: The proposed system enabled standardized graft preparation and construct assembly. Further fatigue, subsidence, and clinically relevant cervical spine model testing are required. Full article

Thermomechanical processing (TMP) is of critical importance for tailoring microstructures and properties of high-strength titanium alloys and their composites. In this study, mechanical response and microstructural evolution mechanisms of 2 vol.% TiB/Ti-5Al-5Mo-5V-3Cr-1Zr (Ti-55531) matrix composites during isothermal compression at varied deformation temperatures (785–925 °C) and strain rates (0.001–1 s⁻¹) are comprehensively investigated by kinetic calculation and microstructural characterization. Strain-compensated constitutive equations in α + β and β phase regions were established. Results show that deformation temperature and strain rate influence flow behavior and microstructure through dynamic recovery (DRV) and dynamic recrystallization (DRX) of the β phase as well as dynamic spheroidization of the α phase. Crucially, three DRX mechanisms of β phase were identified, wherein TiB-induced β-DRX dominates, with α-assisted β-DRX and continuous dynamic recrystallization (CDRX) as secondary mechanisms. Dynamic spheroidization mechanisms of the α phase, including β-wedge penetration as well as α interaction and kinking, were elucidated. A comprehensive microstructural evolution mechanism map was constructed, and an optimized hot-processing window was proposed. Notably, the introduction of TiB significantly promotes β-DRX, which tends to randomize crystallographic orientations of the β phase, and enhances microstructural stability. This study provides theoretical complement and practical guidance for hot processing and microstructure control of metastable β titanium matrix composites. Full article

This study investigated how compositional variation within the AlTiSiCrCo high-entropy alloy (HEA) system affects the microstructure, hardness, and dry sliding wear behaviour of laser-cladded coatings on Ti6Al4V. Three coatings, namely, equiatomic (HEA 1), Cr/Co-enriched (HEA 2), and Al/Ti-enriched (HEA 3), were characterized by SEM, EDS, XRD, and Vickers microhardness and tested for dry sliding wear using a ball-on-disc tribometer at 5 N and 15 N. All coatings comprise a BCC solid solution matrix reinforced by intermetallic precipitates. HEA 2 and HEA 3 gave the highest hardness (755 HV and 754 HV, respectively) against 705 HV for HEA 1 and 345 HV for the Ti6Al4V substrate. All HEA coatings reduced wear rate relative to Ti6Al4V; HEA 2 recorded the lowest rate ($4.570\times {10}^{-5}$ mm³/N.m and $2.744\times {10}^{-4}$ mm³/N.m at 5 N and 15 N, respectively), well below the substrate ($2.257\times {10}^{-4}$ mm³/N.m and $0.0014$ mm³/N.m at 5 N and 15 N, respectively). Worn surface analysis showed abrasive/delamination at 5 N transitioning to more severe abrasive, adhesive, and delamination wear at 15 N. The enhanced wear resistance of HEA 2 stems from the BCC solid solution strengthening, intermetallic reinforcement, and high chromium content, which aids in the formation of the Cr₂O₃ protective oxide film. Overall, enriching the coating with chromium and cobalt proved to be the most effective approach for improving the tribological performance of laser-cladded AlTiSiCrCo HEA coatings on Ti6Al4V. Full article

Introduction/Objectives: The mechanical reliability of prosthetic finger connectors is critical for daily prosthesis use, as these small load-bearing elements transmit forces between finger segments and are prone to localized stress concentration at hinge transitions. The objective of this study was to quantitatively evaluate the mechanical performance of prosthetic finger connectors and determine how material selection influences stress distribution and deformation behavior when connector geometry is maintained constant. Methods: A controlled comparative finite element analysis was performed using COMSOL Multiphysics 6.2 on a single prosthetic finger connector geometry manufactured from four candidate materials: titanium alloy Ti-6Al-4V (E = 110 GPa), polyetheretherketone (PEEK, E = 4.0 GPa), AvaSpire AV-621 NT (E = 3.0 GPa), and KetaSpire KT-820 FP (E = 4.1 GPa). Three representative loading scenarios were simulated using an axial grip force of 50 N and a bending moment of 0.5 N·m: (1) axial loading, (2) combined axial and forward bending, and (3) combined axial and reverse bending. Results: Across all loading conditions, peak von Mises stresses consistently localized at the hinge-transition region of the connector. Ti-6Al-4V demonstrated the lowest peak stress (approximately 2.2 MPa under combined forward bending) and the smallest maximum displacement (approximately 0.0005 mm). In contrast, the PEEK-family polymers showed greater deformation (0.0125–0.0167 mm) due to their lower elastic modulus, while maintaining comparable peak stresses of approximately 2.5–2.6 MPa. The stress profiles along the connector arc length were nearly identical among all materials, indicating that connector geometry primarily governs stress localization, whereas material stiffness mainly determines deformation magnitude. Conclusions: This study demonstrates that material selection strongly affects prosthetic finger connector compliance, while stress concentration behavior is mainly controlled by geometry. The obtained quantitative comparison provides design-oriented guidance for selecting between Ti-6Al-4V and PEEK-based polymers for the development of lightweight and mechanically reliable prosthetic finger connectors. Full article