Search Results (3,545)

TC2 titanium alloy (Ti-4Al-1.5Mn, wt.%) is a near-α titanium alloy with promising aerospace and biomedical applications, but its limited room temperature ductility and strong texture sensitivity hinder the fabrication of high-performance sheets. In this study, the effects of hot rolling at 830 °C and 930 °C on the microstructure, macro-texture, mechanical properties, and fracture behavior of TC2 alloy were investigated. Compared with the 830 °C rolled sample, the 930 °C rolled sample exhibited finer primary α grains, a higher volume fraction of fine and dispersed secondary α_s phase, and more uniform Mn distribution, while both samples retained an α + β phase constitution. Texture and ODF (orientation distribution function) analyses revealed that increasing the rolling temperature reduced the maximum intensity of the (0001) pole figure from 6.68 to 5.23 m.r.d. (multiples of a random distribution) and increased that of the (10-10) pole figure to 9.62 m.r.d., indicating weakened basal texture, enhanced prismatic texture, and more dispersed orientation distribution. Consequently, although the tensile strength slightly decreased to approximately 730 MPa, the elongation increased from approximately 24% to 28%. The finer and denser dimples observed after 930 °C rolling further confirmed improved plastic deformation coordination. Full article

Achieving a favorable synergy of strength, ductility, and toughness is a critical challenge for expanding the engineering applications of titanium alloys. In this work, a medium-strength and high-toughness novel Ti-Al-Mo-V-Cr-Sn-Zr (named Ti62F) titanium alloy in the form of a Φ400 mm bar was adopted to systematically investigate the regulation behavior of double annealing on its microstructure and mechanical properties, and quantitative correlations between microstructural parameters and macroscopic properties were established. Increasing the cooling rate during the first annealing stage (air cooling, force air cooling and water quenching) significantly refined the secondary α (α_s) phase and reduced the volume fraction and size of the primary α (α_p) phase, leading to an increase in the ultimate tensile strength of the alloy from 1077 MPa to 1229 MPa. However, the impact-absorbed energy decreased from 51.5 J to 23.3 J. When the second annealing temperature was varied within the range of 625–675 °C, the ultimate tensile strength fluctuated slightly and the impact toughness increased moderately. Equiaxed α_p phase and relatively thick α_s can induce multiple crack deflections, prolong the crack propagation path and enhance energy absorption. Dislocations are mainly piled up at α/β phase boundaries, triggering void nucleation and growth, which dominate the ductility and toughness levels. Tensile twinning acts only as an auxiliary deformation mechanism and contributes limitedly to toughness. After heat treatment under the optimized schedule of 880 °C/2 h/AC + 650 °C/4 h/AC, the Ti62F alloy exhibits a superior strength–toughness balance compared with conventional medium-strength titanium alloys such as TA15, TC4, and TC4-DT. The findings can provide a heat treatment basis for microstructural regulation of large-size Ti62F bars and their engineering applications in aerospace structural components. Full article

Titanium alloys have been extensively employed in the aerospace industry, and their service performance is largely governed by high-temperature low-cycle fatigue damage. However, investigations into the fatigue behavior of TC25 titanium alloy subjected to corrosion in a marine atmospheric environment remain limited. In this study, high-temperature low-cycle fatigue tests were conducted on TC25 titanium alloy before and after corrosion. It was found that, after corrosion, the proportion of the structural failure stage increased by approximately 10%. The corrosion pits on the surface led to local stress concentration, resulting in an increase in the number of fatigue crack sources and an acceleration of the fatigue crack growth rate, thus reducing the fatigue life of the material. These findings provide important theoretical and experimental support for the application of TC25 titanium alloy in marine environments. Full article

Four alpha-beta titanium alloys, containing increased beta stabilising elements when compared to the well established Ti-6Al-4V, were previously characterised for their low cycle fatigue behaviour and resistance to cold dwell sensitivity. The same four alloys are now assessed for high cycle fatigue performance, employing plain cylindrical and notched specimen geometries. Fatigue strength under load-controlled cycling was measured under two contrasting mean stress conditions, a fully reversed R = −1 waveform and a positive mean stress waveform of R = 0.3. The role of microstructure and micro-texture are considered to explain the relative high cycle fatigue behaviour of each alloy and in particular the mechanisms responsible for fatigue crack initiation. The data are subsequently employed to construct “safe stress” range-mean diagrams. Full article

Background/Objectives: Titanium alloy Ti₆Al₄V remains the gold standard in dental implantology due to its excellent mechanical properties, corrosion resistance, and biocompatibility. However, implant-associated infections and insufficient osseointegration continue to represent major clinical challenges, mainly related to bacterial biofilm formation and suboptimal surface–tissue interactions. Biofilm formation refers to the adhesion, accumulation, and growth of microbial communities embedded within a self-produced extracellular polymeric matrix on implant surfaces, which contributes to bacterial persistence and resistance to host defense mechanisms. This review aims to critically evaluate recent advances in multifunctional bioceramic coatings for dental implants, with a particular focus on zirconia (ZrO₂)-based systems and their antibacterial mechanisms. Methods: A structured literature analysis was conducted using major scientific databases including PubMed, Scopus, and Web of Science, focusing mainly on studies published between 2015 and 2025 related to CaP, Ag, and ZrO₂-based coatings for dental implants. The review examines their physicochemical properties, antibacterial strategies, ion release behavior, and biological responses, including osteogenic activity and biofilm inhibition. Particular attention is given to hybrid systems integrating multiple functional phases. Results: CaP coatings exhibit excellent osteoconductivity and promote early osseointegration but show limited intrinsic antibacterial activity. Ag-based coatings provide strong broad-spectrum antimicrobial effects through controlled Ag⁺ ion release, although concerns regarding cytotoxicity and dose-dependent responses remain. ZrO₂ coatings significantly enhance corrosion resistance and surface stability, while their antibacterial performance can be improved through nanostructuring, laser surface modification, and ionic doping. Hybrid Ag–CaP–ZrO₂ coatings demonstrate improved antibacterial activity, enhanced corrosion resistance, and better regulation of ion release kinetics and osteogenic response compared with single-component coating systems. Conclusions: Multifunctional bioceramic coatings represent a promising strategy for improving the performance of dental implants and addressing the dual challenge of infection control and tissue integration. However, challenges remain regarding long-term stability, controlled ion release, and limited clinical validation. Future research should focus on the development of smart, stimuli-responsive coatings and standardized evaluation protocols to facilitate clinical translation. Full article

To tackle the development of large-capacity titanium shell batteries, resistance spot welding was performed to join 1 mm thick TA2 titanium plate and T2 copper plate with a tungsten electrode on the copper side and a CuCrZr alloy electrode on the titanium side. The microstructure of the interfacial zone of the joint was systematically observed and analyzed, and the tensile shear bearing capacity of the joint was evaluated. At the interface zone in the peripheral region of the weld, a CuTi layer was formed adjacent to the titanium side, and a Cu₄Ti layer was formed adjacent to the copper side; at the interface zone in the central region of the weld, four layers—CuTi₂, CuTi, Cu₄Ti₃, and Cu₄Ti—were formed. The tensile shear load of the joint exhibits a trend of initially increasing and subsequently decreasing as the welding current increases or the welding time extends, and the tensile shear load of the joint reaches the maximum value of 5.50 kN when the welding current is 18 kA and the welding time is 400 ms. The research findings suggest that despite the feasibility of resistance spot welding between titanium and copper by utilizing tungsten electrodes on the copper side, the intermetallic compound layer formed at the welding interface serves as the crucial factor influencing the performance of the joint. Full article

Titanium carbide (TiC) is a technologically important material, which is used in industrial and engineering applications as an abrasive, a wear-resistant material, reinforcement in composites, as well as an electrocatalysis material. This review summarizes the state-of-the-art processes for the synthesis of TiC, for instance, carbothermal reduction, combustion reactions, sol–gel processing, gas phase reaction, and mechanical alloying. Moreover, this review updates the various processes used for the synthesis of nanostructured titanium carbide and its process mechanisms. Nanostructured titanium carbide can be synthesized through optimizing thermal reduction processes, using more reactive titanium-containing precursors, a gas phase reaction or mechanical alloying processes. Under these reaction conditions, reactants are more reactive to overcome the kinetic barriers and the reaction processes proceed at a much lower temperature or have a shorter duration. The sol–gel process allows the formation of nanostructured TiC at a relatively low temperature due to the high reactivity of the sol–gel precursors. Mechanical alloying processing is a versatile method to produce nanostructured TiC. Gas phase processing allows nanostructured TiC formed in particles or in films. Nanostructured TiC has the potential to enhance the performance of TiC as a technological material, which is attractive for various applications in industrial and engineering fields. Full article

This study investigates the damage behavior and surface integrity of chitosan–nanohydroxyapatite (CS/nHAp) composite coatings, along with their corrosion resistance and wettability, which directly affect their biological performance in vivo. The coatings were deposited on Ti13Zr13Nb and stainless steel using electrophoretic deposition (EPD) at various voltages and deposition times. Surface topography, morphology, composition, and roughness were characterized using microscopic techniques, while wettability, corrosion resistance, and mechanical properties were assessed. Three-point bending tests were performed to determine coating behavior under mechanical deformation. Hydrophilic, homogeneous CS/nHAp coatings were successfully deposited without visible cracks on the surface. Coatings deposited at 10 V exhibited higher corrosion potentials compared to uncoated titanium alloy. Mechanical testing showed that coatings deposited at 10 V were significantly harder than those deposited at 20 V. The CS/nHAp20_5 coating exhibited moderate hardness (0.33 ± 0.06 GPa), the lowest Young’s modulus (12.7 ± 1.4 GPa), increased flexibility, and good adhesion, without delamination during bending tests. These results demonstrate that by modifying deposition parameters, it is possible to adjust the mechanical and protective properties of CS/nHAp coatings for potential application of the developed coating in vascular stents. Full article

To achieve accurate prediction of the surface COF (coefficient of friction) of titanium alloys under electrochemical corrosion conditions, this study investigates the tribological behavior of titanium alloys across various solutions, concentrations, voltages, and sliding velocities to construct a systematic dataset. Two machine learning models are developed and optimized: a standard Light Gradient Boosting Machine (LightGBM) and an enhanced LightGBM model incorporating lag and rolling features. These models are employed to predict the friction coefficient and feature importance analysis. The results indicate that solution concentration is the primary factor influencing the friction coefficient of the titanium alloy, followed by test duration, while sliding velocity exerts the least influence. Following experimental validation and iterative optimization, the enhanced LightGBM model, integrated with lag and rolling features, demonstrates superior predictive accuracy, achieving a coefficient of determination (R²) of 0.979 on the training set and 0.951 on the test set. This research establishes a data-driven predictive framework that demonstrates superior accuracy and interpretability compared to models using only raw features, showcasing the potential of feature-engineered machine learning in optimizing electrochemical machining parameters. Full article

Stress shielding (SS) after cementless total hip arthroplasty arises from the stiffness mismatch between conventional Ti-6Al-4V femoral stems (110 GPa) and cortical bone (10–30 GPa). The β-type Ti-33.6Nb-4Sn (TNS) alloy femoral stem addresses this limitation through a continuous Young’s modulus gradient (~70 GPa proximally to ~40 GPa distally) achieved by localized heat treatment of a single homogeneous alloy. This review synthesizes a translational research program encompassing material characterization, finite element modeling (FEM), preclinical animal studies, and prospective clinical follow-up of up to seven years. FEM demonstrated favorable proximal micromotion well below the osseointegration threshold, with physiological proximal stress concentration concordant with clinical outcomes. At seven years, SS grade distribution was significantly lower in the TNS group than in Ti-6Al-4V controls, with SS frequency reduced in Gruen Zones 2, 3, and 6, and no stem-related failures; however, third-degree SS was still observed in 11 of 34 evaluable cases (32%), indicating that modulus-gradient optimization alone is insufficient to fully prevent SS. TNS alloy is currently the only β-type titanium alloy clinically applied in joint prostheses. Remaining challenges include stem geometry optimization, additive manufacturing-based porous structures, and dual-energy X-ray absorptiometry-based bone density quantification. Future directions encompass long-term follow-up, cyclic fatigue FEM simulations, and expansion to fracture fixation devices and dental implants. Full article

Mechanically milled Ti₈₀Ni₂₀ powders were compacted and sintered at various temperatures after being milled for 9 h in a protective atmosphere. Scanning electron microscopy (SEM) was used to evaluate the morphology of the surfaces. Oscillating friction and wear tests were carried out in ambient air using an oscillating tribotester. As a counter pair, we used a ball of Al₂O₃ with a diameter of 6 mm under different conditions of normal applied load for the three sintering regimes. SEM characterizations, the micro- and nano-hardness, roughness measurements, and the friction coefficient were used to study the tribological behavior of the samples’ surface morphology, as well as the weight loss following testing. According to the findings, the resistance to wear and friction of the biomedical Ti₈₀Ni₂₀ alloy can vary depending on the preparation and treatment methods used. Surface coating is recommended to further improve the tribological behavior of the substrates. The novelty of this study lies in the combined investigation of the microstructural evolution and tribological behavior, offering a better understanding of the performance of nanostructured titanium–nickel alloys in engineering applications. Full article

Internal defects cause significant fluctuations in the dispersion of low-cycle fatigue life of titanium–aluminum alloy specimens under fully reversed strain control ($R_{\epsilon }=-1$) at room temperature. To accurately analyze the relationship between internal defects and low-cycle fatigue behavior, this study adopts an energy-based approach to investigate the variation patterns of plastic strain energy density (PSE) during low-cycle fatigue testing of specimens. Research has revealed that the decline process of plastic strain energy dissipation is distinctly divided into two stages, and the low-cycle fatigue life exhibits a pronounced nonlinear relationship with the plastic strain energy dissipation rate (PSEDR) during the first stage. Based on internal defect characteristics obtained from X-ray scans, a defect intensity parameter $K_{t\_micro}$ was proposed to establish a life prediction interval under the influence of internal defects. By correcting the stable plastic strain energy using stress concentration factors, the prediction error of the stable plastic strain energy model was reduced from a 3× error band to a 1.5× error band. The maximum relative error decreased from 132% to 34.30%, significantly narrowing the overall prediction error. Compared with the Mason–Coffin (M-C) model and the stable plastic strain energy model, the prediction accuracy is significantly improved. Full article

The long-term success of orthopedic implants is fundamentally dependent on the synergy between mechanical performance and biological integration. Thus, a comprehensive investigation of both mechanical characteristics and microstructural parameters is essential for the development of reliable implant systems in hip arthroplasty, both in human medicine and veterinary practice. The present study provides a detailed analysis of the mechanical properties, microstructure, and chemical composition of a Ti-6Al-4V-based femoral implant using nanoindentation, scanning electron and optical microscopy, and energy-dispersive X-ray spectroscopy. Then, using finite element analysis, the influence of Young’s modulus on the stress–strain state of the endoprosthesis was evaluated. Dynamic loading conditions were considered by analyzing an impact on a cantilever beam, simulating an animal’s jump onto a supporting limb. For reliable numerical simulation, the model geometry was constructed utilizing computed X-ray microtomography. The numerical simulations were performed for three material cases: reference Ti-6Al-4V, experimentally characterized Ti-6Al-4V (with properties determined by nanoindentation), and CoCrMo alloy, which is also widely used in endoprosthetic applications. The influence of the founded mechanical characteristics on the stress–strain state of the prostheses was assessed. In particular, the results indicate that under dynamic loading conditions, the load-bearing capacity of CoCrMo is lower by approximately 30% and 21% compared to the reference and experimentally characterized Ti-6Al-4V, respectively. Full article

Ti-6Al-4V thin-walled specimens were fabricated by gas tungsten arc welding-based wire arc additive manufacturing under controlled oxygen concentrations of 1, 500 and 1000 ppm, with ambient air used as a severe oxygen-exposure reference. The effects of oxygen concentration on oxygen uptake, microstructure, oxidation behavior and mechanical properties were investigated. Within the controlled range, the internal oxygen content increased from 0.07 to 0.15 wt.%, remaining below the ASTM B381-2013 limit. These specimens retained sound interlayer bonding and were mainly composed of α-Ti with a small amount of β-Ti, without detectable crystalline TiO₂ by X-ray diffraction. Controlled oxygen uptake refined the α lamellae and increased deformation resistance through interstitial solid-solution strengthening, increasing hardness from approximately 320 HV to 330–350 HV and tensile strength from 880 to 940 MPa, while reducing elongation from 11.5% to 9.5%. In contrast, the ambient-air specimen reached an oxygen content of 0.36 wt.%, developed an approximately 90 μm oxidation-affected layer and showed TiO₂-related oxides, α-colony aggregation and interface weakening. Its tensile strength and elongation decreased sharply to 295 MPa and 1.9%, respectively. These results indicate that atmosphere control in WAAM Ti-6Al-4V should prevent the transition from controlled oxygen strengthening to excessive oxygen-induced embrittlement. Full article

Solar-driven NiTi alloy wire rotary engines are promising for lightweight actuation, but their performance is often restricted by insufficient light absorption of the alloy wire and unstable wheel–wire transmission. In this work, a collaborative surface-modification strategy was developed by combining a CNT/PDA-based photothermal coating on the NiTi alloy wire with a CNT/PDMS-based coating on the wheel surface. To establish a controllable wire-coating process, electrophoretic deposition parameters were first screened on titanium plates using an orthogonal design involving voltage, duty ratio, water content, treatment time, and electrode distance. Among the tested conditions, an electrode distance of 10 mm provided the most favorable balance between coating thickness and microstructural uniformity, while water content and electrode distance were identified as the main factors affecting coating variation. After transfer to the alloy wire, the coating greatly reduced reflectance in the 300–1400 nm range and significantly enhanced photothermal heating, increasing the maximum irradiation temperature by about 30 °C. On the wheel side, PDMS-based surface modification further improved rotational output, and the 1.5 wt% + 10 wt% formulation showed the best performance. In coupled rotation tests, the system with simultaneous wire and wheel modification exhibited the fastest startup and the highest angular velocity, reaching about five times that of the slowest rotating modified group. These results demonstrate that coordinated surface modification of the alloy wire and wheel is an effective route to improving the photothermal response and rotational performance of NiTi alloy wire rotary engines. Full article