Cu-Ti Alloys Research Articles

Effect of Cu Content on the Precipitation Behaviors, Mechanical and Corrosion Properties of As-Cast Ti-Cu Alloys.

Ti-Cu alloys have broad application prospects in the biomedical field due to their excellent properties. The properties of Ti-Cu alloys are strongly dependent on Cu content, microstructures, its Ti2Cu phase and its preparation process. The aim of this work is to investigate the effect of Cu content on the precipitation behaviors, mechanical and corrosion properties of the as-cast Ti-Cu alloys. The microstructures and phase evolution were characterized by SEM and TEM, and the properties were studied by tensile and electrochemical test. The results show that the volume fraction of Ti2Cu phase increases with the increase of Cu content. The Ti2Cu phase presents a variety of microscopic morphologies with different Cu content, such as rod, granular, lath and block shaped. The crystal orientation relationships between the Ti2Cu and α-Ti matrix in Ti-4Cu and Ti-10Cu alloys are (103)Ti2Cu//(0[111)α-Ti, [01]Ti2Cu//[20]α-Ti, and (103)Ti2Cu//(0002)α-Ti, [31]Ti2Cu//[110]α-Ti, respectively. The tensile strength, Vickers hardness and Young’s modulus of the Ti-Cu alloys increase with the increase of Cu content, whereas the elongation decreases. The fracture morphologies of these alloys reveal ductile, ductile-brittle hybrid, and cleavage brittle mode, respectively. The corrosion resistance of the Ti-Cu alloys in SBF solution can be described as: Ti-4Cu alloy > Ti-10Cu alloy > Ti-7Cu alloy. The volume fraction of Ti2Cu phases and the “protective barrier” provided by the fine lath Ti2Cu phases strongly affected the electrochemical performances of the alloys.

Improving tensile property and thermal stability of the Cu-Ta alloy by alloying with Cr

The wide applications of Cu-10Ta (at%) composite are limited due to the high cost of Ta element (24 wt%). In the present research, Cu-0.6Ta-0.6Cr and Cu-0.6Ta alloys with low Ta content were fabricated by mechanical alloying and spark plasma sintering. The results indicate that the thermal stability and tensile strength of Cu-0.6Ta-0.6Cr alloy are significantly increased by the addition of Cr. The microstructure characterizations reveal that the performance enhancement of Cu-0.6Ta-0.6Cr alloy is ascribed to the transformation of nanoparticles in the matrix from Ta to more stable Cr2Ta Laves and the refinement effects of these nanoparticles from 19.4 nm to 14.1 nm. This work provides a potential for the wide applications of Cu-Ta alloy with low Ta by alloying with Cr at elevated temperatures.

Tough and wear-resistant carbon fiber reinforced TiC-based composite prepared by alloyed melt infiltration at low temperatures

To improve the toughness and friction properties of carbon fiber reinforced ceramic matrix composite, a Cu alloy modified carbon fiber reinforced TiC based ceramic matrix composite was designed and prepared by TiCu alloy melt infiltration at low temperatures up to 1100 °C. The as-produced composite was mainly composed of carbon, TiC, Ti 3 Cu 4 , TiCu 4 and Cu phases. Due to the ductile Cu alloy introduced into the matrix, the composite showed good mechanical performance especially the fracture toughness. The flexural strength reached about 248.36 MPa while the fracture toughness was up to 15.78 MPa·m 1/2 . The high toughness of the composite was mainly attributed to the fiber bridging, fiber pull-out, interface debonding, crack propagation and deflection. The tribological performance of the as-produced composite was measured using SiC and 440C stainless steel balls as counterparts, respectively. The as-prepared composite exhibited good wear resistance and the wear mechanism was discussed based on the microstructural observations.

Corrosion performance of Ti-Cu alloys targeted for biomedical applications

The Thermo-Calc™ program and TTTI3 database were used to predict the phases in Ti-Cu with 5, 25, and 40 wt% Cu. Based on the predicted results, experimental work was conducted and the Ti-Cu alloys were produced in a button arc furnace, and characterised in the as-cast and the annealed condition (900°C) followed by water quenching. Microstructures and compositions were determined using an electron probe micro-analyser, and the phases were identified by X-ray diffraction. The corrosion performance was measured by potentiodynamic polarisation in a phosphate buffered saline solution at 37 °C at 7.4 pH while purging with nitrogen gas. The Ti-5Cu and Ti-25Cu alloys comprised (αTi) and Ti2Cu phases, the Ti-40Cu alloy comprised Ti2Cu and TiCu. Although the addition of copper decreased the corrosion performance by down to 75%, the corrosion rates were still within the acceptable range (0.02-0.13 mm/y) for biocompatibility of metallic implants. Annealing at 900 °C did not improve the corrosion performance.

To improve the angiogenesis of endothelial cells on Ti-Cu alloy by the synergistic effects of Cu ions release and surface nanostructure

Peri-implant angiogenesis plays important roles in osseointegration of implants. Unfulfilling neovascularization will lead to delayed union or non-union after prosthetic implanted. In this paper, a nanostructured surface composed of TiO2, CuO and Cu2O was fabricated on Ti-Cu alloy using an alkali-heat treatment. The nanostructure strengthened anticorrosion but accelerated Cu ions release. Meanwhile, in vitro cells experiments proved both Cu ions release and nanostructure on the surface of Ti-Cu alloy improved the functionality of human umbilical vein endothelial cells (HUVECs) resulting in excellent pro-angiogenesis potential indicated by promoted initial adhesion and spreading, satisfied cytocompatibility, enhanced migration, improved tube formation, upregulated angiogenesis-related genes and increased VEGF protein secretion. It was suggested that the modified Ti-Cu alloy with desired angiogenesis might be a promising strategy to improve osseointegration.

A nano-structured TiO2/CuO/Cu2O coating on Ti-Cu alloy with dual function of antibacterial ability and osteogenic activity

• A TiO 2 /CuO/Cu 2 O composite coating with nanostructure was deposited on Ti-Cu alloy by alkali-heat treatment. • TiO 2 /CuO/Cu 2 O coating exhibited strong antibacterial ability against S. aureus . • TiO 2 /CuO/Cu 2 O coating promoted initial adhesion and spreading of MC3T3-E1 cells, as well as osteogenic differentiation. Bacteria-associated infection and poor osseointegration are two main reasons for orthopedic implant failure. Ti-Cu alloy exhibited excellent antibacterial property, but still presented unsatisfied osteogenic activities. Therefore, Ti-Cu alloy was surface modified by an alkali-heat treatment in this paper to improve the osteogenic ability without reduction in antibacterial ability. A TiO 2 /CuO/Cu 2 O composite coating with nanostructure was deposited on Ti-Cu alloy. The coating showed increased roughness and great hydrophilicity. Antibacterial tests indicated that the modified Ti-Cu alloy exhibited stronger antibacterial ability against Staphylococcus aureus ( S. aureus ) than Ti-Cu alloy. Meanwhile, cell experiments demonstrated that the composite coating promoted initial adhesion and spreading of MC3T3-E1 cells, enhanced alkaline phosphatase (ALP) activities as well as extracellular matrix (ECM) mineralization, and significantly upregulated osteogenesis-related gene expressions. It was suggested that the nano-structured TiO 2 /CuO/Cu 2 O coating on Ti-Cu alloy might provide a potential strategy for orthopedic implant failure.

Mechanical alloying and amorphization of Ti75Cu25 alloy

Ti-Cu alloys are used in dental and medical applications, due to their good mechanical properties, corrosion resistance and antibacterial properties. These properties are sensitive to microstructure and can be improved by formation of intermetallic compounds or amorphization of crystalline Ti-Cu powder. This study focuses on the amorphization of Ti75Cu25 powders prepared by mechanical alloying (MA). Ball milling, up to 60 h, of Ti and Cu powders leads to an amorphous structure. Laser granulometry, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were carried out for different milling times. Future research on consolidation of amorphous powder via electrical resistance sintering will be performed to obtain bulk samples with amorphous phase and/or nanocrystalline phase with Ti3Cu and/or Ti2Cu intermetallic compounds.

The Effects of 3d-Printed Ti-5cu Alloy on Macrophage Polarization and its Conditioned Medium on Osteogenic Differentiation of Mc3t3-E1 Cells

The Effects of 3d-Printed Ti-5cu Alloy on Macrophage Polarization and its Conditioned Medium on Osteogenic Differentiation of Mc3t3-E1 Cells

Computational mechanical behavior of nanocrystalline copper-tantalum alloy

This study reports the mechanical properties of a nanocrystalline binary alloy using molecular dynamic simulation approach. The analysis has been specifically conducted under uniaxial tensile loading of the crystal lattice. The chosen nanocrystalline material was employed for the analysis of an alloy of copper (Cu) and tantalum (Ta) metals with concentration being Cu60-Ta40. The tensile behavior of the nanocrystalline alloy has been investigated at different temperatures varying from room temperature (i.e. 300 K to 1200 K, ambient pressure, and selective strain rates ranging between 1 × 1010 /sec and 2 × 1010 /sec. Initially, the perfect crystal of the alloy was modelled. The effect of change in temperature and strain rate on stress–strain response of Cu-Ta alloy has been explored. It has been noticed that with the rise in temperature from 300 K to 800 K the elastic constant, ultimate tensile strength and yield strength decreases slowly which becomes more prominent at higher temperatures i.e. 1000 K and 1200 K. Also, the behavioral shift of the stress–strain curve is noticed in an upward direction with increasing strain rates.

On the vacancy nature of the high-temperature background of internal friction in solids

High-temperature internal friction in an amorphous CuTi alloy is investigated. Exponential regions with different activation energies are observed on the dependence of internal friction on temperature on both sides of the glass transition temperature. An exponential increase in the background of internal friction with temperature in both sites is associated with the migration of vacancy-like defects in the amorphous structure under the influence of mechanical stresses, while frozen defects of constant concentration migrate to the glass transition temperature. After the transition to a state of thermodynamic equilibrium, the concentration the number of migrating defects increases exponentially. Based on the experimental results of measuring the high-temperature background, estimates of the activation energy of migration and the formation of vacancies of similar defects in the amorphous structure of the alloy under study are made. Keywords: Internal friction, relaxation time, high temperature background, amorphous alloy.

О вакансионной природе высокотемпературного фона внутреннего трения в твердых телах

High-temperature internal friction in an amorphous CuTi alloy is investigated. Exponential regions with different activation energies are observed on the dependence of internal friction on temperature on both sides of the glass transition temperature. An exponential increase in the background of internal friction with temperature in both sites is associated with the migration of vacancy-like defects in the amorphous structure under the influence of mechanical stresses, while frozen defects of constant concentration migrate to the glass transition temperature. After the transition to a state of thermodynamic equilibrium , the concentration the number of migrating defects increases exponentially. Based on the experimental results of measuring the high-temperature background, estimates of the activation energy of migration and the formation of vacancies of similar defects in the amorphous structure of the alloy under study are made.

Micro-addition of Fe in highly alloyed Cu-Ti alloys to improve both formability and strength

Cu-Be alloys provide excellent electrical and mechanical properties, but present serious health hazards during manufacturing. Among alternative alloys, the Cu-Ti system has the highest yield strength; however, Ti cannot be easily solutionized at concentrations above 4 wt%, resulting in a relatively low formability. In this study, Cu-xTi-yFe (x = 3, 5, 6 wt% and y = 0, 0.3 wt%) alloys were studied after both solution-annealing and age-hardening through mechanical testing and microstructure analysis. Micro-additions of Fe kept high concentration of Ti in solid solution (up to 6 wt%) after water quenching and suppressed the classical “wave-like” early-stage precipitation. Instead, a new dispersion of nano precipitates was observed. This behavior results in doubling the ductility in the solution annealed state (up to 48% elongation), together with maintaining a very high strength after ageing (up to 975 MPa) from precipitation of metastable nano α-Cu4Ti. This study shows that Fe micro-additions, when combined with a higher amounts of Ti (6 wt%), enables the production of Cu-based alloys combining high formability and strength, providing an excellent alternative to Cu-Be in mechanical applications.

Preliminary study on biocorrosion inhibition effect of Ti-5Cu alloy against marine bacterium Pseudomonas aeruginosa

Titanium is not fully immune to the microbiologically-influenced corrosion, yet highly susceptible to biofouling. Biocorrosion inhibition effect of Ti-5Cu alloy against Pseudomonas aeruginosa was studied using antibacterial test, various electrochemical techniques and surface analysis. Ti-5Cu alloy was verified to effectively reduce the MIC rate. After 14 days of incubation in P. aeruginosa, the icorr of cp-Ti (89.20 ± 12nA cm−2) was significantly greater than that of Ti-5Cu alloy (35.42 ± 5.3nA cm−2). Release of Cu2+ ions which was confirmed by shake-up feature controlled respiration of P. aeruginosa, resulting in strong pitting resistance ability. The outermost layer of Ti-5Cu alloy was predominantly composed of TiO2, but a spot of Ti° was also detected. In contrast, the content of Ti2O3 at sputtering thickness of 0, 2, and 6 nm was higher on the surface of cp-Ti compared with Ti-5Cu alloy. Ti2Cu intermetallic compounds promoted the rapid self-healing property of passive film in the presence of P. aeruginosa.

Ultrastable Cu Catalyst for CO2 Electroreduction to Multicarbon Liquid Fuels by Tuning C-C Coupling with CuTi Subsurface.

Production of multicarbon (C2+ ) liquid fuels is a challenging task for electrocatalytic CO2 reduction, mainly limited by the stabilization of reaction intermediates and their subsequent C-C couplings. In this work, we report a unique catalyst, the coordinatively unsaturated Cu sites on amorphous CuTi alloy (a-CuTi@Cu) toward electrocatalytic CO2 reduction to multicarbon (C2-4 ) liquid fuels. Remarkably, the electrocatalyst yields ethanol, acetone, and n-butanol as major products with a total C2-4 faradaic efficiency of about 49 % at -0.8 V vs. reversible hydrogen electrode (RHE), which can be maintained for at least 3 months. Theoretical simulations and in situ characterization reveals that subsurface Ti atoms can increase the electron density of surface Cu sites and enhance the adsorption of *CO intermediate, which in turn reduces the energy barriers required for *CO dimerization and trimerization.

Ultrastable Cu Catalyst for CO2 Electroreduction to Multicarbon Liquid Fuels by Tuning C–C Coupling with CuTi Subsurface

AbstractProduction of multicarbon (C2+) liquid fuels is a challenging task for electrocatalytic CO2 reduction, mainly limited by the stabilization of reaction intermediates and their subsequent C−C couplings. In this work, we report a unique catalyst, the coordinatively unsaturated Cu sites on amorphous CuTi alloy (a‐CuTi@Cu) toward electrocatalytic CO2 reduction to multicarbon (C2‐4) liquid fuels. Remarkably, the electrocatalyst yields ethanol, acetone, and n‐butanol as major products with a total C2‐4 faradaic efficiency of about 49 % at −0.8 V vs. reversible hydrogen electrode (RHE), which can be maintained for at least 3 months. Theoretical simulations and in situ characterization reveals that subsurface Ti atoms can increase the electron density of surface Cu sites and enhance the adsorption of *CO intermediate, which in turn reduces the energy barriers required for *CO dimerization and trimerization.

High-energy ball milling of intermetallic Ti-Cu alloys for the preparation of oxide nanoparticles

Copper and titanium oxides in the nano-size range show unique chemical and physical properties and thus have been intensively considered for novel and smart applications. In this work, oxide nanoparticles were prepared by high-energy ball milling of Ti-Cu alloys followed by a controlled oxidation process. Alloys of the Ti-Cu system Ti-50Cu, Ti-57Cu, and Ti-65Cu (in wt.%) prepared by arc melting were selected considering they provide different starting brittle intermetallic phases before milling. Microstructural investigation indicated that Ti-50Cu was composed of Ti2Cu and TiCu, while Ti-57Cu was single-phase TiCu. Ti-65Cu was dual-phase and consisted of Ti3Cu4 and Ti2Cu3. A mean particle size below 10 nm was achieved after high-energy ball milling for all compositions. The oxidation process was then investigated in two temperature ranges. At high oxidation temperatures of 700–800 °C, a complete oxidation took place leading to oxides TiO2-rutile and CuO in all alloys. However, at a low oxidation temperature (350 °C), partial oxidation occurred and different oxides were obtained. Ti-50Cu was the most promising alloy and led to a mix of TiO2 (rutile and anatase), CuO, Cu2O, and Ti3Cu3O. After long exposure to thermal oxidation, the resulting oxides remained in the nanometric range with a particle size distribution showing a D50 of approximately 6 nm.

Helium partitioning to the core-shelled Ta nanoclusters in nanocrystalline Cu-Ta alloy

In this work, a nanocrystalline (NC) Cu-10at.%Ta alloy is irradiated with helium at different temperatures to assess the stability and effectiveness of Ta nanoclusters in trapping helium and suppressing swelling. Advanced microstructural characterization of the room-temperature irradiated specimens indicated the presence of small He-bubbles (∼1-2 nm) at the peak damage depth mainly at the core and along the interface of Ta nanoclusters with Cu matrix. Few bubbles were found along grain boundaries, with much smaller bubbles homogenously distributed within the copper lattice. High-temperature irradiation exhibited bubbles of ∼3-5 nm, which were primarily associated with nanoclusters as compared to other locations, with no observed faceting of the bubbles. Atom probe analysis confirmed helium partitioning to the Ta nanoclusters indicating the effective entrapment of these He atoms.

Biocompatibility and antibacterial properties of TiCu(Ag) thin films produced by physical vapor deposition magnetron sputtering

Mechanical robustness, biocompatibility, and antibacterial performance are key features for materials suitable to be used in tissue engineering applications. In this work, we investigated the link existing between structural and functional properties of TiCu(Ag) thin films deposited by physical vapor deposition magnetron sputtering (MS-PVD) on Si substrates. Thin films were characterized by X-ray diffraction (XRD), nanoindentation, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The TiCu(Ag) films showed complete amorphous structure and improved mechanical properties in comparison with pure Ti films. However, for contents in excess of 20% Ag we observed the appearance of nanometric Ag crystallite. The TiCu(Ag) thin films displayed excellent biocompatibility properties, allowing adhesion and proliferation of the human fibroblasts MRC-5 cell line. Moreover, all the investigated TiCu(Ag) alloys display bactericidal properties, preventing the growth of both Pseudomonas aeruginosa and Staphylococcus aureus. Results obtained from biological tests have been correlated to the surface structure and microstructure of films. The excellent biocompatibility and bactericidal properties of these multifunctional thin films opens to their use in tissue engineering applications.

Dissolution kinetics of irregular second phase in as-cast Cu-Ti alloys via a multi-particle dissolution model

The morphology of the second phases formed during the solidification is irregular in many alloy systems, making precise simulation of their dissolved evolution difficult. In this work, a multi-particle spherical log-normal distribution was used to simulate the dissolution of such irregular second phase and took the as-cast Cu-Ti alloy as a case study. The dissolution of the as-cast Cu4Ti phase was simulated via a multi-particle dissolution model integrating the CALPHAD-based diffusion theory (CALPHAD: CALculation of PHAse Diagrams) and high-throughput calculations. The 5041 sub-models (spherical log-normal distributions) replacing the size distribution of the as-cast Cu4Ti phase were initially generated based on the mass balance. Then, 2.5×106 data points in 491 sub-models selected from 5041 sub-models were calculated to fit the experimental DSC curves based on the energy conservation, and the best-fitted sub-model could be determined finally. Based on this sub-model, the volumetric and energetic evolution of the as-cast Cu4Ti phase during various dissolution processes could be predicted, and the simulated results were confirmed to be in agreement with the present experimental results. Also, a counterintuitive self-coarsening phenomenon of the Cu4Ti phase has been observed during heating, which has been approved in the experimental work.

Hybrid processing of TiC/TiCu/C composites with tailored hardness

This work reports the effect of TiC volume fractions on hardness of TiC/TiCu/C composites synthesized through in situ reactive infiltration of Ti-Cu alloy into porous carbon preforms prepared by 3 D-printing. Reactive melt infiltration of the alloy at 1100 °C under argon into C-preforms with different porosities resulted in materials composed of TiC, Cu-rich intermetallic matrix (Ti3Cu4) and residual carbon. The microstructure consists of TiC grains distributed along the Cu-Ti/C boundary. The hardness of TiC/Ti3Cu4/C composites could be tailored by the TiC volume fraction and the distribution in the composites, which are determined by the processing parameters and the initial porosity of the carbon templates in 3 D-printing stage. The hardness of the produced composites ranges from 350 HV to 570 HV and could be tailored by the TiC volume fraction and distribution in the composites, which are determined by the processing parameters and the initial porosity of the carbon-preforms.