CoCrMo alloys are widely used as orthopedic and dental implants, owing to their superior mechanical properties, wear resistance, and biocompatibility. Copper (Cu) ion exhibits strong antibacterial activity, making it a promising alloying element. A systematic study was conducted on the corrosion resistance and ion release behavior of CoCrMo-xCu (Co-xCu) alloys in both as-cast and heat-treated states in different simulated solutions. The results indicated that the corrosion resistance of Co-xCu alloys decreased with the increasing Cu content, which was mainly attributed to the formation of micro-galvanic couples between the alloy matrix and Cu-rich phases. The synergistic effect of heat treatment and an appropriate Cu content can effectively improve the corrosion resistance of the alloys, and the corrosion current density (icorr) of Cu-containing cobalt alloys was comparable to that of Cu-free cobalt alloys. Maximum concentrations of Co, Cr, and Cu ions released from Co-xCu alloys were lower than the corresponding recommended safety limits. Through the combined optimization of Cu content and heat treatment, the metal ion release levels of Cu-containing cobalt alloys can be reduced to values even lower than those of Cu-free cobalt alloys.

Copper-containing antibacterial titanium alloys become a hot-topic and show promising application prospects in the field of orthopedic implants. However, their antibacterial properties are closely related to the Cu content, but excessively high Cu levels may induce cytotoxicity and compromise mechanical properties. To address this, an microalloying Ti-1wt% Cu alloy was surface modified by surface mechanical rolling treatment (SMRT) and acid etching (AE) to synergistically improve its corrosion resistance, antibacterial and biocompatibilities. The resulting GNS Ti-1Cu-AE alloy exhibits a typical micro-nano hierarchical structure, consisting of a nanocrystalline layer (similar to 98 nm) with uniformly distributed submicron etching pits, along with the formation of TiO2 and Cu2O. Electrochemical tests indicate that SMRT treatment significantly enhanced corrosion resistance. Antibacterial tests show that GNS Ti-1Cu-AE achieved antibacterial rates exceeding 95% against both Staphylococcus aureus and Escherichia coli, primarily attributed to the synergistic effects of sustained Cu(2+)release, contact-based antibacterial effect of Cu2O. In vitro cell experiments reveal that GNS Ti-1Cu-AE promoted the early differentiation activity of osteoblasts, which is manifested as an increase in alkaline phosphatase activity. This work provides new insights into the development of orthopedic implant materials that combine biosafety with functional performance.

This study develops a multi-scale material removal model for ultrasonic vibration-assisted polishing (UVAP) to bridge macroscopic process parameters with microscopic abrasive cutting behavior through a mesoscopic perspective. By integrating ultrasonic vibration principles and contact mechanics, a macroscopic contact model between polishing pad and workpiece surface is first established. From a meso-scale viewpoint, abrasive particles within contact area are categorized as embedded and free types. Corresponding microscopic material removal models are then formulated based on indentation hardness theory, Hertzian contact theory, the law of energy conservation, and other relevant principles. Building on the mesoscopic analysis, a material removal rate (MRR) model for contact area is constructed, incorporating a radial scraping cutting frequency function for embedded abrasive particles and an impact count function for free abrasive particles in a single ultrasonic vibration period. The predicted results from the model deviate from experimental data by no more than 6 %. Based on the established model, further simulation studies under varying polishing parameters reveal the effect characteristics of ultrasonic vibration on intermediate variables during material removal process in UVAP, elucidate the scientific essence of why ultrasonic vibration enhances polishing performance, and provide a reliable theoretical basis for understanding and optimizing the UVAP process.

Oral biomedical materials are susceptible to microbiologically induced corrosion (MIC) during long-term service, which may compromise their clinical performance and therapeutic efficacy. Herein, a 90-day experimental model was established to systematically investigate the MIC behavior of commercially pure Ti and Ti5Cu alloy under challenge of cariogenic Streptococcus mutans. Biofilms developed progressively on both materials, whereas Ti5Cu supported markedly thinner and less mature than pure Ti, with maximum thicknesses of 41.2 ± 3.1 and 55.1 ± 4.2 μm after 90 days, respectively. Continuous electrochemical measurements revealed lower corrosion susceptibility of Ti5Cu, as evidenced by higher polarization resistance, larger capacitive arc radii, and lower corrosion current density. S. mutans biofilms induced pronounced pitting corrosion, with maximum pit depths reaching 4.3 and 3.1 μm on Ti and Ti5Cu, respectively. AFM results further revealed increased surface roughness and potential heterogeneity on Ti, suggesting enhanced micro-galvanic effects. Nevertheless, Ti5Cu effectively mitigated these effects, likely owing to its ability to suppress biofilm formation and interfacial acidification. These findings provide a theoretical basis for understanding the long-term corrosion mechanisms of titanium-based oral materials and guiding material design for their safe service.

The two main problems with titanium implants are bacterial infection and insufficient osseointegration. The balance between osteoinductivity and antibacterial activity remains a formidable challenge because toxicity is usually introduced with enhancement of the antibacterial ability. In this research, a nanostructured fluoride-doped hybrid tantalum oxide (TaFO) was prepared on titanium by plasma-based surface modification. By a change of the fluorine-oxygen ratio, the fluorination/oxidation (F/O) level was optimized, and the dual effects of antibacterial activity and osteogenic promotion were achieved. The TaFO samples exhibited remarkable antibacterial abilities when the surface F/O proportion level exceeded 0.11. The antibacterial effect of the sample may be caused by the combined action of multiple factors: the superhydrophilic coating inhibits bacterial adhesion, the metal oxide induces oxidative stress, and the F--induced acidified microenvironment inactivates adenosine triphosphate (ATP) synthesis and induces bacterial oxidative stress. In addition, with a proper F/O level, the TaFO-II sample not only significantly promoted the proliferation and differentiation of osteoblasts, enhanced alkaline phosphatase (ALP) activity and extracellular matrix mineralization, and increased the expression levels of important osteogenic genes in vitro but also effectively resisted bacterial infection, accelerated bone regeneration, and promoted osseointegration. In conclusion, this study introduces an approach to successfully imparting selective antibacterial and osteogenic properties to titanium implants, which has a large potential to simultaneously address the issues of bone regeneration and infection in clinical applications.

The corrosion resistance and antibacterial properties of Ti-3Cu alloy prepared by selective laser melting were evaluated using electrochemical experiments and a variety of antibacterial characterization. It is found that the charge transfer resistance of Ti-3Cu alloy was 4.89x105 Omega center dot cm2, which was doubled the data obtained by CP-Ti alloy. The antibacterial rates of Ti-3Cu alloy against S. mutans and P. gingivalis were 45.0% and 54.5%. And the antibacterial rates increased with the prolongation of cultivation time, reaching up to 62.8% and 68.6%, respectively. The in-situ nano Ti2Cu precipitates were homogeneously distributed in the matrix of the Ti-3Cu alloy, which was the key reason of increasing the corrosion resistance. Additionally, the microscale electric fields between the alpha-Ti matrix and the Ti2Cu was responsible for the enhancement of the antibacterial properties.

The ability of osseointegration of implants is an important factor in ensuring the long-term stability of bone implants in their recipient sites. In this paper, Ti-M titanium alloys with different surface micro-area potential difference (MAPD) were prepared and the adhesion, proliferation, spreading, and differentiation behavior of osteoblasts (MC3T3) on the surface of Ti-M alloy were investigated in detail to reveal the effect of MAPD on cell compatibility and osteogenic differentiation. The results showed that the alloy with high MAPD facilitated bone differentiation, demonstrating that MAPD significantly enhanced the alkaline phosphatase activity and mineralization ability of osteoblasts, and upregulated the expression of osteogenic differentiation-related factors. It is suggested that it might be a strategy to promote the surface bioactivity of titanium alloy by adjusting the surface MAPD.

To address the issue of burst release of Zn2+ ions in the early degradation stage of degradable zinc alloys and enhance their cellular activity, a composite coating consisting of PLGA and Mg(OH)2 was prepared on the surface of Zn alloys. The incorporation of Mg(OH)2 serves two purposes: on one hand, it regulates the pH value; on the other hand, it releases Mg2+ ions to improve cytocompatibility. A series of tests, including electrochemical corrosion testing, ion dissolution testing, sample morphology observation, and cytotoxicity testing, was conducted to investigate the morphology, degradation process, ion release, and cytocompatibility of the coating. The results demonstrate that the composite coating can effectively reduce the release of Zn2+ ions, regulate the pH value after coating degradation, and control the release of Mg2+ ions, thereby significantly reducing the toxicity to osteoblasts and improving its biocompatibility.

Excellent antibacterial capability and low elastic modulus are critical for titanium alloys used in orthopedic implants. Ti-13Nb-13Zr (TNZ), a representative low-modulus near-beta alloy, gains significant antibacterial capability through copper alloying. However, optimizing by conventional heat treatment processes often tend to metastable phase transition, which significantly elevates the elastic modulus. To overcome this limitation, this study employed laser surface treatment (LST) to modify the surface of Ti-13Nb-13Zr-5Cu (TNZ-5Cu) alloy, aiming to construct a Ti2Cu precipitate layer to enhance the antibacterial activity without increase in the overall elastic modulus. Research results have shown that a nanoscale Ti2Cu precipitate layer was created on the alloy surface by controlled laser-induced thermal effect. This approach preserved the sample's elastic modulus at a low value (77 GPa), while significantly increased surface hardness (> 450 HV) and antibacterial performance (> 99 % reduction). LST improved surface roughness, hydrophilicity and corrosion resistance. Additionally, the initial adhesion and spreading of MC3T3-E1 cells was promoted, demonstrating excellent biocompatibility. Overall, the laser-induced Ti2Cu precipitate layer simultaneously achieved an ideal balance between elastic modulus and antibacterial activity of TNZ-5Cu alloy, while significantly optimized surface hardness, corrosion resistance, and cytocompatibility, thereby exhibiting great potential for the application in medical metal-based implant materials.

In this article, plasma electrolytic oxidation (PEO) is applied to Ti–4.5Cu alloy to prepare a Cu2O/CuO containing coating to improve the antimicrobial properties and cytocompatibility. Scanning electron microscopy and X‐ray photoelectron spectroscopy are used to characterize the surface microstructure as well as the elemental valence states, and electrochemical tests and inductively coupled plasma spectroscopy are used to determine the corrosive properties and Cu‐ion release behavior, and the antimicrobial properties are evaluated by plate counting method and the cytotoxicity is evaluated by methylthiazolyldiphenyl‐tetrazolium bromide (MTT) method. In the results, it is shown that PEO treatment significantly improves the hardness, hydrophilicity, roughness, corrosion resistance, and accelerated Cu‐ion release. In the plate counting method results, it is shown that the antimicrobial capacity of Ti–4.5Cu alloys is significantly increased to >99.9% after the PEO treatment due to multiple effects of the release of Cu ions and the formation of Cu2O and CuO. Furthermore, PEO treatment promotes the proliferation of L929 cells while the surface morphology after sandblasting has a further value‐added effect on cell adhesion. It is concluded that Cu ion and the surface morphology play a decisive role in the adhesion and proliferation of the cells.

Bacterial infection and poor bone formation on implant surfaces always cause implantation failure. The synergistic effect of bioactive nanostructures with fluoride and silver ions is expected to resist implant infection and promote osteogenesis. In this paper, a nanostructured fluoride-doped TiOx films were deposited on Ti-0.5 wt% Ag alloy (Ti-0.5Ag/FO) by plasma-based surface modification to reveal the synergistic interaction of nanostructures with fluoride and silver ions on the antibacterial and osteogenic activity. By using this platform, antibacterial and osteogenic properties in vitro and in vivo were evaluated. The Ti-0.5Ag/FO has intense antibacterial properties against both Staphylococcus aureus and Escherichia coli. The collaboration of F- and Ag+ would synergistically enlarge their antibacterial properties by destroying the normal metabolic activities of bacteria, changing the membrane potential, producing ROS, and affecting ATP synthesis and protein synthesis, thereby leading to bacterial death. Meanwhile, Ti-0.5Ag/FO can enhance ALP activity, promote ECM mineralization, and significantly enhance osteogenic-related genes' expression, thereby obtaining excellent cytocompatibility and osteogenic capability in vitro. Moreover, even under bacterial infection conditions, this material significantly facilitated in vivo new bone tissue deposition and improved the integration efficiency of the implant-bone interface. This study presents a novel implant design strategy that exhibits superior bone integration and antibacterial properties, offering broad clinical application potential in orthopedics and dental implants.

gamma-TiAl based alloys are advanced structural materials use in the automotive and aerospace industries. Their notable characteristics, including low density, high specific yield strength, and exceptional resistance to creep and oxidation, make them highly viable for being used as structural components in high-temperature applications of internal combustion engines. The novel beta-solidifying gamma-TiAl alloy designed in this study demonstrated excellent oxidation resistance at temperatures of 750, 800, and 850 degrees C. However, research regarding the solid-state phase transformations and microstructure control of this alloy is lacking. The study of the phase transformation behavior and microstructural evolution of alloys is crucial for developing appropriate thermal processing and heat treatment techniques for beta-solidifying gamma-TiAl alloys. This work introduces a novel Ti-Al-Mn-Nb alloy, with a nominal composition of Ti-43Al-1.5Mn-3Nb-0.2Si-0.2C-0.1B (atomic fraction, %). Using Pandat software for thermodynamic calculations, along with techniques such as EPMA, TEM, EBSD, and XRD, an extensive and meticulous investigation of the microstructural transformations within the range from 1440 degrees C to 1000 degrees C for this innovative alloy was undertaken. The results indicate that the as-cast microstructure of the alloy comprises a lamellar colony (alpha(2)/ gamma), grain gamma phase, and a small amount of beta(o). The solidification pathway of the alloy can be determined as follows: liquid -> liquid + beta ->beta ->beta + alpha ->alpha ->alpha + gamma ->(alpha(2) + gamma)->(alpha(2) + gamma) + beta(o)->(alpha(2) + gamma) + beta(o) + gamma(g). The temperature at which the alloy exists as a single beta phase (T-beta) is approximately 1420 degrees C, while the decomposition temperature of gamma phase (T-gamma,T-solv) is approximately 1280 degrees C; additionally, the eutectoid transformation temperature (T-eut) is approximately 1160 oC. Slightly below T-gamma,T- solv, the gamma precipitated from the alpha phase exhibits a lamellar structure. The alpha and gamma phases consistently demonstrate a Blackburn orientation relationship: (111)(gamma)//(0001)(alpha 2) and <1<(1)over bar>0>(gamma)//<11<(2)over bar>0>(alpha 2), respectively. The secondary beta(o) phase precipitated from the alpha phase appears as a block shape and follows the Burgers orientation relationship: (110)(beta O)//(0001)(alpha 2) and <111>(beta O)// <11<(2)over bar>0>(alpha 2). The Vickers hardness of the quenched microstructure of the novel alloy ranges between 385 and 512 HV. With an increase in the quenching temperature, there is an observable enhancement in the microhardness of the quenched microstructure. The martensite microstructure formed after quenching in the beta single-phase area contributes to the hardness of 512 HV. This novel alloy encompasses the beta and alpha single-phase areas; thereby holding significant implications for the development of novel, highly deform-able, and high-temperature-resistant beta-solidifying gamma-TiAl alloys characterized with fully lamellar structures.

Antibacterial Ti-5Cu alloy is a promising substitute material for Ti-made cardiovascular implants, so its surface engineering is crucial to expediting clinical implementation. Given the antibacterial and cardiovas-cular biological benefits of Cu2 + and titanium-nitride-oxide (TiNxOy) coatings, a Cu2O/CuO-TiNxOy coating with upregulated Cu2+ release was successfully deposited on Ti-5Cu alloy for the first time using oxygen and nitrogen plasma-based surface modification. The superhydrophilic and nanostructured Cu2O/CuO-TiNxOy coating had a dense structure and was well bonded to the substrate, resulting in enhanced corrosion resistance, while CuO/Cu2O in the coating released Cu2 + faster than Ti2Cu phase in the matrix. More gratifying, the coating demonstrated perfect antibacterial properties ( R > 99.9% against S. aureus), owing primarily to direct contact sterilization of Cu2O/CuO. The most encouraging phenomenon was that the coating dramatically accelerated HUVEC adhesion (1.4 times), proliferation (RGR: 106%-116%), and particularly migration (RMR: 158%-247%) compared with the control Ti. The coating extract also significantly stimulated in vitro angiogenesis capacity. The rapid endothelialization for Cu2O/CuO-TiNxOy coating was attributed to the surface nanostructure and Cu2 +/NO2- release, which upregulated the angiogenesis-related gene expression of HIF-1 alpha, VEGF, and eNOS to increase VEGF secretion and NO production. All of the findings indicated that the Cu2O/CuO-TiNxOy coating could enhance the corrosion resistance, antibacterial properties, and endothelialization potential of Ti-Cu alloy, displaying great clinical potential in cardiovascular applications. (c) 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Bioinert titanium (Ti) with antibacterial properties is crucial for bone implantations. Alloying Ag can endow Ti with antibacterial properties, while the mechanical, corrosion and antibacterial properties of Ti-Ag alloys are not satisfactorily balanced. In this work, Ti-x wt%Ag alloys (x=0.5, 1 and 3) were sintered by spark plasma sintering and then subjected to a surface mechanical rolling treatment (SMRT). The Ti-Ag alloys are composed of Ti, Ti-Ag and Ti2Ag phases. After SMRT, a gradient nanostructured (GNS) layer formed on the Ti-Ag surface, the mean grain size is similar to 6 nm at the top surface and increases gradually with depth. The GNS layer endows Ti-Ag alloys with better wettability, higher nano-roughness and compressive residual stress. Incorporating limited Ag (<= 1 wt%) in Ti can effectively enhance its mechanical (surface hardness, wear resistance and compressive strength) and anti-corrosion properties, and they can be further improved by forming a GNS layer. The antibacterial efficiency of Ti-Ag is positively proportional to Ag content, and they are significantly enhanced after surface nanocrystallization. The bacteriostatic mechanism is the synergistic interaction between leach Ag+ and nano Ag-containing phases of GNS Ti-Ag alloy. Both Ti-Ag and GNS Ti-Ag alloys possess good cytocompatibility, the GNS layer has the potential to encourage early differentiation of osteoblasts. The GNS Ti-Ag alloy with 1 wt% Ag has excellent comprehensive properties, which shows larger potential in orthopedic applications.

In this paper, Ti-5Mn alloy was subjected to different heat treatments to explore the possibility of preparing antimicrobial Ti-Mn alloys and to examine the effect of precipitate on the properties of the alloy. The microstructure, phase composition, hardness, biocorrosion properties and antimicrobial properties of Ti-5Mn alloys after different heat treatments was analyzed by metallurgical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), microhardness tests, electrochemical tests and antimicrobial tests. The results have shown that the phase composition of the solid solution treated Ti-5Mn(T4) was mainly β -Ti phase, and the aged Ti-5Mn was composed of α -Ti phase and Ti _17 Mn _3 phase, while Ti _17 Mn _3 precipitate gradually increased with the extension of the aging time. Ti-5Mn(T4) showed the highest hardness and the best corrosion resistance and the aging process reduced the hardness of Ti-5Mn(T4) alloy. With the precipitation of Ti _17 Mn _3 , the corrosion resistance of the alloy became worse and the hardness was reduced, but the corrosion resistance of Ti-5Mn alloy was still better than that of cp-Ti. It was demonstrated that Ti-5Mn(T4) exhibited no antibacterial properties against Staphylococcus aureus , but the aging treatment improved the antibacterial property of Ti-5Mn(T4) alloy, and the antibacterial rate of Ti-5Mn alloy reached 69% after 50 h aging treatment.

For the application of titanium and titanium alloys in orthopedic implant materials, the antibacterial properties and cell biocompatibility determine whether the implant surgery is successful. In this study, a functional anodic oxidation (AO) coating was successfully prepared to modify the surface of Ti-Ag alloy. The surface characteristics of the anodized Ti-Ag alloy were analyzed using techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. The corrosion characteristics of Ti-Ag samples were tested by an electrochemical workstation. In addition, the antibacterial properties and cell activity were studied by the plate count method and MC3T3-E1 cell staining. The results indicate that the AO process can generate a multi-functional TiO2/Ag2O coating with a large number of block and flower-like structures on the surface of a Ti-Ag alloy. When the AO voltage of the sample is 120 V, the maximum roughness is 0.73 μm and the minimum wetting degree is 23°, which improves the biocompatibility. The corrosion test results show that AO treatment can improve the corrosion resistance of a Ti-Ag alloy. The oxidation voltage is 20 V and the coating has the best corrosion resistance. The corrosion open circuit potential (Eocp) is 107.621 mV and the corrosion current density (icorr) is 2.241 × 10−8 A·cm−2. This coating can promote ion release and show more than 99% of a strong antibacterial ability against S. aureus. The results of the compatibility evaluation by cultured cells showed that the multifunctional coating formed by the anodic oxidation process did not cause cytotoxicity and promoted the adhesion of MC3T3-E1 cells.

Compared with traditional Ti-based biomaterials, in recent years Cu-bearing titanium alloys have been considered among the most attractive metallic biomaterials for oral implants, owing to their excellent antibacterial properties. In this paper, the effects of the Cu content, the existing form of Cu element, and the oral environment on the tribocorrosion resistance of Ti-Cu alloys were investigated in comparison with pure titanium (cp-Ti). The results revealed that a low pH and (especially) a high fluoride ion concentration accelerated the tribocorrosion. The Ti-Cu alloys showed a higher tribocorrosion resistance than cp-Ti in all the simulated solutions tested, owing to the precipitation of nano-Ti2Cu during the aging treatment.

The effect of the extrusion process on the microstructure, corrosion, and mechanical properties of Mg–Zn–Ca–Zr alloy has been investigated. Zn and Ca were both in a solid solution and only the Zr-rich phase was observed in the homogenized and extruded alloys. The Zr-rich phase was obviously refined after extrusion. The corrosion rate of the homogenized alloy decreased by about 25% after extrusion. This is because the refined Zr-rich phase was easier to cover with the deposited corrosion products, which reduced the cathodic reaction activity of the Zr-rich phase. The corrosion rate is similar for the alloys extruded at 320 °C and 350 °C since the size and distribution of the Zr-rich phase were not different in the two conditions. The alloy extruded at 320 °C has a smaller grain size and better comprehensive mechanical properties.

This study examined macrophage morphology, ROS levels, and the RNA expression of inflammatory factors on Ti-M (M = Zr, Ta, Mo) alloy surfaces with varying surface micro-area potential difference (MAPD). Results have shown that MAPD modulated the inflammatory response by affecting macrophage polarization, reducing the RNA expression of pro-inflammatory cytokines, increasing the RNA expression of anti-inflammatory ones, and promoting a shift towards the M2 macrophage state. However, overhigh MAPD levels raised ROS and worsen inflammation.