Cu-Ti Alloys Research Articles

Equiatomic Ti-Cu alloys synthesized by powder metallurgy and melting techniques

Equiatomic Ti-Cu alloys synthesized by powder metallurgy and melting techniques

Enhanced antibacterial activity of Ti-Cu alloy by selective acid etching

Titanium‑copper (TiCu) alloys showed potential application in clinical field due to their excellent antibacterial properties. A selective acid etching (SAE) was applied to TiCu alloy in order to further improve the antibacterial properties. The phase constitute and the surface microstructure were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), the corrosion properties and Cu ion release behavior were measured by electrochemical testing and inductively coupled plasma spectrometry (ICP), the antibacterial property was assessed by a plate-count method and the cell compatibility was evaluated by CCK-8 test. It was shown that more Ti2Cu particles were exposed on the surface of TiCu sample after SAE treatment, which increased the corrosion current density and accelerated the Cu ion release due to the galvanic corrosion between Ti-Ti2Cu couple. The plate counting results demonstrated that the antibacterial ability of TiCu alloy was significantly enhanced from 79% to >99.9% by SAE treatment due to the multifunction of increased Ti2Cu phase on the surface, Cu ion release and the formation of Cu2O. Besides, no cytotoxicity was detected to MC3T3-E1 cells on all test samples.

Microstructural characteristic and mechanical properties of titanium-copper alloys in-situ fabricated by selective laser melting

In this paper, Ti-Cu alloys were in-situ fabricated by selective laser melting (SLM) with 1.25, 2.5 and 5 wt% Cu contents, namely Ti-1.25Cu, Ti-2.5Cu and Ti-5Cu, respectively. The microstructural characteristic and mechanical properties of Ti-Cu alloys were systematically investigated. The results showed that the SLM-fabricated Ti-Cu alloys have a fine microstructure, and the morphology of martensite exhibited a transition from parallel-sided plates or laths to acicular plates with increasing Cu content. Due to the accommodation effect of the martensitic transformation strain, the 14–20% of the martensite partitioning interfaces was constituted of {101̅1} twin boundaries. The microhardness, yield strength and ultimate tensile strength were enhanced synergistically with increasing Cu content, which can be attributed to the combined effects of grain-boundary strengthening, solid-solution strengthening, dislocation strengthening and precipitation strengthening.

The effect of Cu content and Ti2Cu precipitation on the combustion behaviour and mechanism of Ti-xCu alloys

The combustion behaviour and mechanism of Ti-Cu alloys are studied systematically by PIC tests of a series of Ti-xCu alloys. The formation and distribution of Ti2Cu phase at different areas show different effects during combustion process. The liquid Ti2Cu layer at the solid-liquid interface can prevent oxygen diffusion. The molten Ti2Cu phase at grain boundaries in heat affected zone can absorb the energy and inhibit the burning velocity. The width of the Ti2Cu layer and the volume of the molten Ti2Cu phase are considered as the key factors controlling the burning velocity, according to the mathematical model established herein.

Construction of a TiO2/Cu2O multifunctional coating on Ti-Cu alloy and its influence on the cell compatibility and antibacterial properties

Inflammation and infection caused by implants are serious problems in the clinical application of titanium and titanium alloy. Titanium copper alloy has shown strong antibacterial properties, but the surface bioactivity is still necessary to be modification to improve biocompatibility. In this paper, a TiO2/Cu2O multifunctional coating was prepared on Ti-5Cu alloy by an anodic oxidation process in order to enhance the surface bioactivity without affecting the antibacterial ability. The surface physical and chemical properties of the anodized Ti-Cu alloys were tested by X-ray diffraction (XRD), X-ray photo-electron spectroscopy (XPS), scanning electron microscopy (SEM), Vickers hardness tester, contact angle tester and laser confocal microscope, and the corrosion properties were studied by inductively coupled plasma mass spectrometer and electrochemical workstation. The results have shown that the roughness, the hydrophilicity, the copper ion release the corrosion resistance were increased by the anodization in a voltage dependent way. The effect of the anodization was evaluated on the antibacterial properties and cell bioactivity. It was shown that pure titanium did not have antibacterial properties after the anodization. However, the anodization significantly improved the antibacterial properties of titanium copper alloy due to the formation of TiO2/Cu2O coating. No cytotoxicity was found on Ti-5Cu alloys and the anodized Ti-5Cu alloys but the treatment accelerated the cell adhesion. It was suggested that anodization treatment might be a potential surface biomodification method for the clinical application of titanium copper alloys.

Anti-infection mechanism of a novel dental implant made of titanium-copper (TiCu) alloy and its mechanism associated with oral microbiology

This work was focused on study of anti-infection ability and its underlying mechanism of a novel dental implant made of titanium-copper (TiCu) alloy. In general, most studies on antibacterial implants have used a single pathogen to test their anti-infection ability using infectious animal models. However, dental implant-associated infections are polymicrobial diseases. We innovatively combine the classic ligature model in dogs with sucrose-rich diets to induce oral infections via the canine native oral bacteria. The anti-infection ability, biocompatibility and underlying mechanism of TiCu implant were systematically investigated in comparison with pure Ti implant via general inspection, hematology, imageology (micro-CT), microbiology (16S rDNA and metagenome), histology, and Cu ion detections. Compared with Ti implant, TiCu implant demonstrated remarkable anti-infection potentials with excellent biocompatibility. Additionally, the underlying anti-infection mechanism of TiCu implant was considered to involve maintaining the oral microbiota homeostasis. It was found that the carbohydrates in the plaques formed on the surface of TiCu implant were metabolized through the tricarboxylic acid cycle (TCA) cycles, which prevented the formation of an acidic microenvironment and inhibited the accumulation of acidogens and pathogens, thereby maintaining the microflora balance between aerobic and anaerobic bacteria.

Biocompatibility and Cu ions release kinetics of copper-bearing titanium alloys

• Biocompatibility of Cu-bearing titanium alloys meets requirements of ISO standards. • Cu ions release kinetic from Ti-Cu alloy is in line with the zero-order model. • Ti6Al4V-Cu and Ti-Cu have satisfactory biocompatibility both in vitro and in vivo . To reduce the risk of implant-associated infections, we previously designed and developed a series of medical copper (Cu)-bearing titanium alloys that release Cu ions and hence play an antibacterial role. However, both excessive and deficient Cu levels adversely affect human health; therefore, the aim of the present study was to comprehensively evaluate the short- and long-term biosafety of Cu-bearing titanium alloys (Ti6Al4V-Cu and Ti-Cu) both in vitro and in vivo . Moreover, the predominant kinetic mechanism of Cu ions release and its effect on biosafety were also investigated. The results indicate that the biocompatibility of the Cu-bearing titanium alloys meets the requirements of ISO standards and the Cu ion release kinetics display a good correlation over the entire time period in the normal zero-order model with an almost constant release rate. The release rate maintained at a parts per billion level safe for humans; consequently, we can conclude that our Cu-bearing titanium alloys have satisfactory biocompatibility.

Effect of Cu on the passivity of Ti–xCu (x = 0, 3 and 5 wt%) alloy in phosphate-buffered saline solution within the framework of PDM-II

The effect of copper content on the passivity of Ti–xCu alloys in a phosphate-buffered saline electrolyte (pH 7.4), in the steady-state condition, was examined using potentiostatic polarization, electrochemical impedance spectroscopy, and Mott-Schottky analysis. The study demonstrates that the oxide layer forms on the Ti–xCu alloys surface have n-type semiconducting character, and the steady-state thickness of the oxide layer is observed linearly and depends on the applied potential. The study observations are in line with the predictions of the Point Defect Model (PDM-II), which provides a physiochemically realistic description of the oxide layer formation on Ti–xCu alloys. The observations reveal that the Cu additions result in a decrease in the charge transfer resistance and capacitances associated with the hydroxide and barrier layer, an increase in the donor density, and reduce the electrochemical resistance of the Ti–xCu alloys. The study also exhibits that the decrease in the steady-state current density after the initial addition of 3 wt% of Cu is attributed to the progressive substitution of copper on the cation sublattice of the film resulting in enhanced electrostatic interaction between the immobilized copperCuTix′, and the mobile cation interstitialsCui+, which carries the excess current over and that conveyed by oxygen vacancies Vo•• in the barrier layer. Moreover, it is also observed that over a hundred-year implant period, about 0.006 cm (0.06 mm) of Ti–3Cu alloy is predicted to lose due to steady-state corrosion in the PBS solution under the given set of conditions, it is further seen that, as the Cu amount increased from 3 wt% to 5 wt% in the Ti–xCu alloys, the steady-state corrosion rate decreases.

Effects of surface roughening on antibacterial and osteogenic properties of Ti-Cu alloys with different Cu contents

In order to reduce implant-related infections and improve early osseointegration, we performed HF+ anodic oxidation on the surface of the new antibacterial Ti-Cu alloy to make the titanium-based implants have a micro/submicron structure. On this basis, a series of surface-modified Ti-xCu alloys with different Cu contents (3, 5 and 7 wt%) were fabricated and a comprehensive study was conducted on MC3T3-E1 cell adhesion, proliferation, apoptosis and its antibacterial activity against Staphylococcus aureus. Results showed that the Ti-xCu alloys by HF etching + anodized possessed multifunctional characteristics of antibiofilm and antibacterial abilities, excellent biocompatibility and osteogenesis promoting abilities. Increment of Cu content significantly contributed to the antibacterial and osteogenic properties of HF etching + anodized Ti-Cu alloys. Cell proliferation rates of HF etching + anodized Ti-7Cu alloys were lower than those of Ti-3Cu and Ti-5Cu alloys, while the early cell apoptosis rates were higher than Ti-3Cu and Ti-5Cu groups. All the above results finally presented that the HF etching + anodized Ti-5Cu alloy exhibited extremely strong antibacterial properties, good biological compatibility and osteogenic ability, as well as the most excellent ductility and corrosion resistance, providing a great potential application for the future dental implantation.

Fabrication and Degradation Properties of Nanoporous Copper with Tunable Pores by Dealloying Amorphous Ti-Cu Alloys with Minor Co Addition

3D bicontinuous nanoporous copper (NPC) with tunable structure was facilely synthesized by one-step chemical dealloying of Ti-Cu amorphous alloys with minor Co addition (0, 4 and 6 at.%). As-dealloyed NPC shows a sandwich-like hierarchical porous structure with micropore in the inner layer and mesopore in the outer layer. The pore size of NPC can be adjusted by the Co content and corrosion time. In addition, the minor Co element in the matrix alloy can promote the formation of more uniform pore and ligament of NPC, which was evaluated by the surface diffusivity of NPC. The formation mechanism of NPC was discussed using phase separation theory. The NPC/Cu2O composite consists of a large number of 3D continuous ligaments and few tetrahedral Cu2O particles grown on the NPC substrate. As catalysts, NPC/Cu2O composite exhibits excellent degradation performance for methyl orange (MO) dye in the dark assisted by the ultrasonic irradiation due to hierarchical porous structure and the synergistic effect of Cu ligaments and Cu2O particles. The relationship between the efficient MO degradation rate of NPC/Cu2O catalysts and temperature has been discussed. Fenton-like reaction shows that NPC/Cu2O catalysts supplemented with hydrogen peroxide (H2O2) can generate HO· radicals, which resolve MO dye molecules into H2O, CO2 and inorganic species.

Role of tantalum concentration, processing temperature, and strain-rate on the mechanical behavior of copper-tantalum alloys

Microstructural instability in traditional nanocrystalline metals limits the understanding of the fundamental effect of grain size on mechanical behavior under extreme environmental conditions such as high temperature and loading rates. In this work, the interplay between Ta concentrations and processing temperature on the resulting microstructure of a powder processed, fully dense Cu-Ta alloy along with their tensile and compressive behavior at different strain rates are investigated to probe the possibility of manipulating or tuning microstructurally dependent parameters to control the flow-stress upturn phenomenon. Consequently, the results reveal that there is a crucial length scale, i.e., small grain size and appropriate cluster spacing, below which such upturn is damped out. The observation of changes in flow stress upturn behavior is consistent with the observed changes in measured high-rate plasticity, which enhances below the critical length scale. Furthermore, tension-compression asymmetry also tends to be suppressed in nanocrystalline Cu-Ta alloys, while it becomes evident as the grain size increases to an ultrafine regime. Overall, this work presents a systematic approach to control or engineer reduced high strain rate flow stress upturn behavior in metallic alloys, for high-rate applications.

Corrosion and antibacterial performance of novel selective-laser-melted (SLMed) Ti-xCu biomedical alloys

Ti-xCu biomedical alloys were designed to have satisfactory antibacterial properties compared to pure Ti. Ti-xCu (x = 0, 3, 5, 7, and 10 wt%) alloys were prepared by selective laser melting (SLM) using powders of pure Ti and pure Cu. Increasing Cu content decreased the grain size, increased the amount and size of Ti2Cu particles, and increased the hardness. The electrochemical experiments revealed that Ti-5Cu had the best corrosion resistance, and excessive Cu decreased the corrosion resistance. In vitro culture of MG63 cells showed that SLMed Ti-xCu had good cytocompatibility. In vitro antibacterial test of E. coli showed that SLMed Ti-3Cu presented a stable highly-effective antibacterial rate (antibacterial rate>99%), in which the Cu content of 3 wt% was lower than the minimum copper content requirement of 5 wt% in conventional-processes manufactured Ti-Cu alloys that presented a stable highly-effective antibacterial rate. The mechanisms of corrosion and antibacterial performance were clarified. The SLMed Ti-xCu with antibacterial ability is a promising biomedical implant material. The content of the Cu was recommended to be 3~5 wt%.

Multiscale exploit the role of copper on the burn resistant behavior of Ti-Cu alloy

"Titanium fire" can cause catastrophic consequences for machinery components made of titanium alloys, especially in the case of aero-engines. As such, there is continuing interests in developing burn resistant titanium alloys. The burn resistant functionality and mechanical strength of titanium alloys rely on their microstructural characteristics that are significantly determined by the alloying components. This work investigated the burn resistant performance of Ti-Cu alloy and analyzed the role of alloying Cu. With sufficient content of Cu in the system, the formation of Cu rich layer cuts off the oxygen transfer pathway and hinders the burning process. Meanwhile, the addition of Cu results in the reduction of chemical kinetics. For the Ti-Cu alloy with insufficient Cu content, the burn resistance is sacrificed by the discontinuous Cu-rich clusters, among which oxygen penetration prolongs the burning process. Apart from the Cu-rich protective layer, various burning processes accompanied with oxidation products are detected via reduced area X-ray diffraction along the burnt cross section. This work provides a comprehensive understanding of the impacts of Cu content on the burn resistant characteristics of Ti-Cu alloy, which offers theoretical foundation of burn resistant mechanism to the design and fabrication of high-performance titanium alloys.

Effect of Precipitation Hardening on Corrosion Resistance of Cu-4.5 wt.%Ti

Cu-Ti alloys are one of the main candidates to act as a substitute for Cu-Be alloys due to their more environmentally friendly nature. Cu-Ti alloys are age hardenable alloys, and their treatments can modify their microstructure, causing the formation of various Cu-Ti intermetallic that can strongly influence both the mechanical and corrosion properties. In this work, the effect of homogenization heat treatment at 1173 K followed by aging at 723 K for different times (0–24 h) on the microstructure, corrosion and mechanical properties of Cu-4.5 wt.%Ti alloy was investigated. Moreover, the corrosion mechanism based on the different kinetics for the formation of the protective oxide layer was studied. The microstructure and phase analyses were analyzed with SEM and XRD. The mechanical properties were investigated by microhardness test, whereas the corrosion properties were studied by potentiodynamic anodic polarization and potentiostatic tests in artificial sweat. The results showed that the cast sample had the highest corrosion resistance, and the mechanical properties decrease with the homogenization treatment and increase after the combination of homogenization and aging. A corrosion mechanism correlated to the amount and type of intermetallic material was proposed.

Stabilization of Nanocrystalline Copper by Tantalum Grain Boundary Segregation

Nanocrystalline Cu-Ta alloy films were deposited on glass slides by magnetron sputtering. Microstructure characterization proved that most of the tantalum atoms are segregated in the grain boundaries. Nanoindentation creep measurements were performed on it to uncover the stability mechanism of grain boundary segregation on nanocrystalline materials. It is found that segregation can effectively slow down the creep strain rate and the grain boundary activities. The suppressed grain boundary activities endow the alloy with a stable microstructure during plastic deformation and annealing.

Preliminary study of adsorption behavior of bovine serum albumin (BSA) protein and its effect on antibacterial and corrosion property of Ti-3Cu alloy

The adsorption behavior, antibacterial, and corrosion properties of a Ti-3Cu alloy were studied in a phosphate-buffered saline solution containing 0, 1, 3, and 6 g L−1 bovine serum albumin protein at 37 °C and pH = 7.4 (±0.2). The protein adsorption behavior was examined via cyclic voltammetry, secondary ions mass spectroscopy (SIMS), and angle-resolved X-ray photoelectron spectroscopy (ARXPS). The corrosion property was analyzed by the open circuit potential (OCP), potentiodynamic polarization (PD), and electrochemical impedance spectroscopy (EIS) examinations. The antibacterial test was conducted according to the GB/T 21510 China Standard. It was observed that the surface charge density (QADS) was directly proportional to the amount of the adsorbed BSA protein, signifying that the protein adsorption was accompanied by the charge transfer, pointing to chemisorptions phenomena. BSA amino groups and other organic species were observed in the surface analysis examinations. It was shown that the formation of barrier complexes between the TiO2 oxide-layer and PBS solution resulted in decreasing the release of Cu-ions, which consequently reduced the antibacterial activity. On the other hand, these barrier complexes improved the corrosion resistance by increasing the charge transfer resistance and double-layer capacitance of the Ti-3Cu alloy.

Estimation of Enthalpy of Formation of TiCu by Density Functional Method

Abstract—The enthalpies of formation of γ- and δ-modifications of the TiCu phase were estimated using the density-functional method. The enthalpies of formation are –22 and –12.8 kJ/mol for the γ- and δ-TiCu, respectively. The comparison of X-ray data and quantum-chemical calculations demonstrates that the discrepancy in the experimental values of enthalpy of formation of the TiCu crystals correlates with different content of the γ and δ modifications in the TiCu alloy.

Local atomic and crystal structure of rapidly quenched TiNiCu shape memory alloys with high copper content

This study aims to reveal features of the local crystal structure and environment in the quasi-binary TiNi–TiCu alloys containing 25–40 at.% Cu, by X-ray diffraction and EXAFS spectroscopy. The alloys were produced in an amorphous state by the melt-spinning technique and then crystallised by isothermal and electropulsing treatment. It was shown that Ni local structure is more disordered in comparison with Cu local environment, which is closer to the conventional crystallographic structure. An increase in the Cu content resulted in the magnification of the disordering in the nearest local environment, around both the Ni and Cu atoms, consisting of Ti atoms. No noticeable effect of the annealing rate on the local structure was found.

Thermally Activated Jamming in Ultrasonic Powder Compaction

Herein, the role of thermal softening in ultrasonic powder compaction is assessed by comparing the densification behaviors of nominally pure Cu and a thermally stable CuTa alloy. These materials have similar thermal properties, but pure Cu softens at much lower temperatures than does the CuTa alloy. Using a specialized ultrasonic powder compaction setup, in situ measurements of relative density, sonotrode power consumption, and temperature are collected, which together provide a time‐dependent geometric hardening parameter that reflects the structure of the compact. The geometric hardening data for the pure Cu powder reveal three distinct stages of densification: an initial particle rearrangement stage; a jamming transition where strong junctions develop between particles; and a final stage characterized by compatible plastic deformation. By contrast, the geometric hardening data for the thermally stable CuTa powder show that it remains a weak fluidized granular medium, despite experiencing higher normal pressures, oscillation amplitudes, and temperatures. The contrasting behaviors of the Cu and the CuTa powders suggest that a thermally activated jamming transition drives interparticle junction growth and densification in ultrasonic powder compaction.

Joining tungsten with steel for DEMO: Simultaneous brazing by Cu-Ti amorphous foils and heat treatment

Abstract Development of a reliable technology to join tungsten with steel is essential for DEMO application; however, it is difficult due to large differences in their physical properties. To solve this problem, high-temperature brazing was carried out. Cu-Ti brazing alloys, which were rapidly solidified into foil, were used together with a compensating vanadium interlayer, so the EK-181 steel/Cu-28Ti/V/Cu-50Ti/W and EK-181/Cu-50Ti/V/Cu-50Ti/W brazed joints were obtained. The microstructures of the seams were investigated by optical microscopy, SEM (EDX, EBSD) and synchrotron XRD. Thermocycling and shear strength tests showed that Cu-28Ti wt. % brazing alloy ensures a firmer joint compared to Cu-50Ti wt. %. The Cu-28Ti wt. % brazing alloy was used to perform high-temperature brazing in the brazing mode equivalent to traditional EK-181 steel heat treatment. It showed that every step of the heat treatment affected the microstructures and the shear strength.