Cu-Ti Alloys Research Articles

Achieving optimal wear performance for highly-eutectic Cu-Ti alloys via the liquid-solid reaction approach

A series of Cu-Ti alloys have been prepared by the liquid-solid reaction approach at a high vacuum environment. Resultant solidified microstructures have demonstrated highly-eutectic features, which are mainly composed of typical CuTi and CuTi2 phases. Vicker hardness tests have shown that the hardness values of CuTi and CuTi2 are 304 ± 15 HV and 683 ± 27 HV, respectively. Quantitative phase identification has indicated that, as the Ti content increases from 53 at% to 61 at%, the volume fraction of eutectic structure increases initially but decreases afterward, which are 18.8 ± 3.4%, 94.6 ± 3.5% and 54.4 ± 4.5%, respectively. The optimal wear performance has been achieved when the Ti content reaches 57 at%, which is concurrent to the highest volume fraction of the eutectic structure (94.6 ± 3.5%). Our findings may pave a viable yet economic way of fabricating wear resistant alloys in a controllable manner. Data availabilityNo data was used for the research described in the article.

Laser directed energy deposited, ultrafine-grained functional titanium-copper alloys tailored for marine environments: Antibacterial and anti-microbial corrosion studies

The microorganism-rich nature of the ocean imposes great challenges to the structural integrity of metals over their service lifespan, including titanium (Ti) alloys, which are usually prone to microbiologically influenced corrosion (MIC). So, multifunctional anti-MIC Ti alloys need to be developed and studied. This paper investigates the effect of copper (Cu) concentration on the MIC resistance of a series of additively manufactured, ultrafine-grained Ti-xCu (x= 3.5, 6.5 and 8.5 in wt.%) alloys. The dependence of the corrosion resistance and MIC resistance on the Cu concentration of Ti-Cu alloy is interpreted considering all conceivable mechanisms. The mechanisms for excellent corrosion resistance of Ti-Cu alloy in seawater are attributed to the strong passive film and small surface potential difference between phases. Microstructural characterization reveals that uniformly distributed, nanosized Ti2Cu phase led to increased reactive oxygen species in the bacterial membrane, which is the root reason for the superb anti-bacterial property (99.2%) for Ti-8.5Cu. Compared to pure Ti and Ti-6Al-4V, Ti-8.5Cu alloy features both high strength (yield stress > 1000 MPa) and the best MIC resistance (97.5%). The combination of such balanced properties enables this functional 3D printed Ti-Cu alloy to become an ideal material for load-bearing applications in the marine environment.

Ti-Cu積層造形合金における熱処理による析出形態の制御と機構解明

Intermetallic compounds (IMCs), known for their hardness, play an important role in the precipitation strengthening of alloys. However, precipitation in excessive amounts or as large particles can result in embrittlement of the material. Thus, controlling the distribution of IMCs among the matrix is crucial for the design of strong and ductile alloys. In this research, a supersaturated Ti-Cu alloy formed by Laser Powder Bed Fusion (L-PBF) was heat-treated at different phase regions to produce lamellar, network, and dispersed distributions of Ti2Cu IMC precipitates. To comprehensively understand the formation mechanisms of each IMC distribution structure, in-situ microstructure observation was performed during the heat-treatments. The lamellar IMC structure obtained from heat treatment above the beta-transus temperature, was found to derive from the rejection of Cu atoms towards the boundaries of lamellar alpha grains formed during cooling. The network IMC structure obtained from heat-treatment in the α+β phase region involved the formation of a Cu-rich β-Ti layer between α-Ti grains during heating, and subsequent precipitation of Ti2Cu into an α-encapsulating network upon cooling. Finally, the dispersed structure of IMCs was observed to result from regular nucleation and growth of Ti2Cu during heat treatment in the α+IMC region.

Preparation of CuxSb/Ti Electrodes by Electrodeposition and their Sodium Storage Performance

AbstractTo explore a simple and green synthesis method for constructing high‐performance Sb‐based electrodes for sodium‐ion batteries, four CuxSb alloy films with different compositions are deposited on Ti substrates through constant current step technique using SbCl3 and CuCl2 ⋅ 2H2O as raw materials (referred to as CuxSb/Ti). Among them, the prepared Cu1.33Sb/Ti electrode exhibits the best comprehensive electrochemical performance. At a current density of 0.2 A g−1, the electrode has a first reversible capacity of 385.2 mAh g−1 with a coulombic efficiency of 76.7%. After 150 cycles, the reversible capacity remains at 343.5 mAh g−1 with a capacity retention of 89.2%. A stable discharge capacity of 290.5 mAh g−1 can be obtained at a current density of 2 A g−1. The excellent electrochemical performance is attributed to the introduction of inactive Cu, which alleviates the destruction of the volume variation during charging and discharging and improves the conductivity of the electrode. At the same time, CuTi alloy formed from Cu with Ti substrate enhances the bonding force between the alloy film and the substrate. This work provides a new approach for the preparation of Sb‐based alloy anodes for sodium‐ion batteries with low cost, high performance, and free of adhesives and conductive agents.

Enhanced mechanical, bio-corrosion, and antibacterial properties of Ti-Cu alloy by forming a gradient nanostructured surface layer

To improve the comprehensive performance of Ti-Cu alloy, a gradient nanostructured surface (GNS) layer was formed on Ti-Cu alloy by surface ultrasonic rolling treatment (SURT). The surface features, mechanical properties, corrosion resistance, antibacterial properties, and cell compatibility of Ti-Cu alloy before and after SURT were systematically investigated. The surface of GNS Ti-Cu is mainly composed of Cu2O and TiO2, as well as a small amount of Ti, and shows improved wettability. The thickness of the GNS layer is ~200 μm and the average grain size in the topmost layer is ~4 nm. The mechanical properties (microhardness, strength-ductility synergy, and wear resistance) and corrosion resistance are enhanced due to the existence of GNS layer on Ti-Cu alloy. The antibacterial tests demonstrated that GNS Ti-Cu obtains excellent antibacterial ability against Staphylococcus aureus and Escherichia coli, the antibacterial mechanism can be attributed to the accelerated Cu2+ leaching and the contact sterilization of Cu2O. Finally, biocompatibility experiments via MC3T3-E1 cells indicated that GNS Ti-Cu possesses improved cell spread ability and osteoblastic differentiation, showing satisfied biocompatibility. This work demonstrated that Ti-Cu alloy with superior comprehensive performance can be achieved by forming a GNS layer, which has great application potential in the field of metallic biomaterial.

Metal forming and working of stabilized nanocrystalline Cu-Ta for electrical contacts

The commercialization of nanocrystalline metals and alloys is currently entering a renaissance period. Many of the processing and consolidation challenges that have haunted them are now more fully understood, opening the doors for stabilized nanocrystalline metals to be produced on a bulk scale. While challenges remain, the increased volume at which these materials are being supplied is for the first time allowing for investigations into more traditional methods of metal working, such as extruding, rolling, forming, and forging. Recently, the manufacturing science has been developed to allow nanocrystalline Cu-Ta alloys to progress to this point. This article therefore builds upon the last decade of evolutionary progression within the family of stabilized nanocrystalline Cu-Ta alloys by presenting some of the first findings related to scaled powder synthesis, production of billets, thin sheets, and foils. The mechanical performance and physical properties relevant to forming electrical contacts and pins including, tensile, J-integral fracture toughness, Charpy Impact, bi-axial tension, and conductivity are reported. This introductory investigation into forming such a novel material, provides evidence to these alloys potential at bridging the gap between being a scientific curiosity to that of a real engineering material.

Selection of spot welding electrode material by AHP, TOPSIS, and SAW

Upsetting of electrode tip contacts due to heat and contact pressure effects on current density leading to deprivation of spot welding electrode material becomes a major concern in high volume production automotive industry. Along with Electrical conductivity, strength and wear resistance are equally important properties for spot welding electrode material, however very few materials exhibit all these properties. An objective of this research is to rank the spot welding electrode material based on AHP, TOPSIS, and SAW. Analytical Hierarchy Process (AHP) was used in the selection of critical properties. In this work, a total of eight distinct classes of Cu-Be Cu-Cd, Cr-Zr, Cu-Cr-Zr, Cu-W, and Cu-Ti alloys were ranked using TOPSIS and SAW multi-criteria decision-making methods. It is observed that C16200 (i.e. Cu-Cd) and C18150 (i.e. Cu-Cr-Zr) are the most suitable materials for spot welding of mild steel sheets/plates. However, the selection is based on availability, manufacturability, environment protection rules, and cost. Though C16200 ranked first, considering cost-effectiveness C18150 is recommended for this application. This paper suggested an approach for the selection of durable spot welding electrode material to achieve high weld quality. Further research on metallurgical adaptations at contact geometry needs to be conducted.

Copper release and ROS in antibacterial activity of Ti-Cu alloys against implant-associated infection

Copper release and ROS in antibacterial activity of Ti-Cu alloys against implant-associated infection

Dealloying of an amorphous TiCuRu alloy results in a nanostructured electrocatalyst for hydrogen evolution reaction

AbstractDevelopment of an electrocatalyst that is cheap and has good properties to replace conventional noble metals is important for H2 applications. In this study, dealloying of an amorphous Ti37Cu60Ru3 alloy was performed to prepare a free‐standing nanostructured hydrogen evolution reaction (HER) catalyst. The effect of dealloying and addition of Ru to TiCu alloys on the microstructure and HER properties under alkaline conditions was investigated. 3 at.% Ru addition in Ti40Cu60 decreases the overpotential to reach a current density of 10 mA cm−2 and Tafel slope of the dealloyed samples to 35 and 34 mV dec−1. The improvement of electrocatalytic properties was attributed to the formation of a nanostructure and the modification of the electronic structure of the catalyst. First‐principles calculations based on density function theory indicate that Ru decreases the Gibbs free energy of water dissociation. This work presents a method to prepare an efficient electrocatalyst via dealloying of amorphous alloys.

Processing and properties of powder metallurgy Ti-Cu-Nb alloys

Binary Ti-Cu and Ti-Nb alloys have been extensively studied for biomedical applications, but the potential of ternary Ti-Cu-Nb alloys, where the combined benefits of adding Cu and Nb on the performance of biomedical Ti alloys is harvested, has not been fully exploited. Therefore, this study aims to investigate the processing and properties of Ti-Cu-Nb alloys obtained via powder metallurgy. Independently of their actual chemistry, the studied Ti-Cu-Nb alloys are characterised by a lamellar microstructure, which is refined by the incremental addition of Cu+Nb, and a eutectoid substructure is formed for sufficiently high contents of Cu. The balance between slightly higher residual porosity and the microstructural changes, including the stabilisation of a greater amount of β phase, a lamellar structure with refined features, and the precipitation of the Ti2Cu intermetallic phase, leads to a monotonic linear increment of the resistance to plastic deformation. However, the ductility initially increases for small additions of Cu+Nb and subsequently decreases due to the change in failure mode induced by the progressively higher impact of the residual pores. The studied Ti-Cu-Nb alloys share the same strengthening mechanism and have better strength/ductility pairs with respect to binary Ti-Cu and Ti-Nb alloys and better elongation compared to cast Ti-Cu-Nb alloys.

Antibacterial copper-bearing titanium alloy prepared by laser powder bed fusion for superior mechanical performance

• A boundary engineering strategy is proposed to improve the strength and ductility of materials simultaneously. • The addition of Cu successfully verified the feasibility of the boundary engineering strategy, and improved the comprehensive mechanical properties of LPBF martensitic titanium alloy. • The role of copper addition in microstructure development are clarified. • The strengthening mechanism of LPBF Ti, Ti-5Cu and Ti-6Al-4V is explained by calculation and fitting. Copper element was added in pure titanium to produce a new biomedical titanium-copper alloy by laser powder bed fusion (LPBF). Addition of copper can eliminate the mismatch of high strength but poor ductility problem caused by lath α' martensite, which is the usual microstructure of near α titanium alloy fabricated by LPBF. Instead of by the usual trade-off relationship between strength and ductility, which is a long-standing challenge for martensitic titanium alloys, in this study, we proposed a boundary engineering strategy and aim to synergistically enhance the strength and ductility of martensitic titanium alloy fabricated by LPBF. It is hypothesized that whilst both low-angle and high-angle grain boundaries are beneficial to the strength, high-angle grain boundary can simultaneously improve the ductility of materials. To test this strategy, a Ti-5Cu (wt.%) alloy is selected to compare against pure titanium and Ti-6Al-4V at the same laser processing conditions. EBSD, TEM and XRD analysis show that the as-fabricated LPBF Ti-5Cu alloy is comprised of partially tempered martensite with extraordinarily high number density of both high-angle and low-angle grain boundaries as well as low dislocation density. Such microstructure enables a high tensile strength of 940–1020 MPa, which is at a similar level as LPBF Ti-6Al-4V, and an excellent elongation of 13%–16%, twice as much as that of LPBF Ti-6Al-4V. The mechanism of microstructure refinement in LPBF Ti-5Cu at different levels from prior-β grains, martensitic packets, blocks to laths is also discussed.

Relationship of the atomic dynamics and excess volume of a copper rich Cu76Ti24 alloy melt

We investigate the atomic dynamics of a Cu-rich Cu76Ti24 alloy between 1223 K and 1453 K using the quasi-elastic neutron scattering technique. The obtained mean Cu/Ti self-diffusion coefficient D exhibits an Arrhenius-like temperature dependence with an activation energy of 0.46�0.02 eV per atom. Compared with those of the pure elements at a given temperature, D is slower than that for pure Cu, but similar to pure Ti. This slowing down of the liquid dynamics upon alloying has been observed for most binary alloy systems. However, in this study, the packing fraction of the Cu-Ti alloy is lower than that of the pure elements, which can be explained by the positive excess volume of the Cu-Ti system. Therefore, the compositional dependence of the atomic dynamics cannot be linked to a macroscopic packing argument. Only, the atomic dynamics is not correlated with an increase of the average packing fraction of the melt.

Effect of Cold Working on the Properties and Microstructure of Cu-3.5 wt% Ti Alloy.

Cu-Ti alloys were strengthened by β'-Cu4Ti metastable precipitation during aging. With the extension of the aging time, the β'-Cu4Ti metastable phase transformed into the equilibrium β-Cu4Ti phase. The Cu-3.5 wt% Ti(Cu-4.6 at% Ti) alloys with different processing were aged at different temperatures for various times after solution treatment at 880 °C for 1 h. The electrical conductivity of samples under different heat treatments had shown an upward trend as time increased during aging, but the hardness reached the peak value and then decreased. The hardness and electrical conductivity of the samples with 70% deformation after aging are higher tha n the samples without deformation. Deformation after aging would cause the metastable phase to dissolve into a matrix. The best combination value of conductivity and hardness is 13.88% IACS and 340.78 Hv, and the optimal heat treatment is 500 °C for 2 h + 70% deformation + 450 °C for 2 h.

Improvement of biocorrosion resistance and antibacterial performance of Ti-3Cu alloy subjected to laser shock peening

Ti-Cu alloys have attracted much attention in the field of orthopedics and dentistry. The existence form of Cu is a main factor influencing the bacterial response and corrosion resistance. Laser shock peening (LSP) is increasingly applied as an effective technology for enhancing the properties, especially the corrosion resistance of different metallic components. Present work is focused on the examination of the effects of LSP treatment on the phase constituents, microstructure and surface grain size of the samples, and the relevant surface related properties such as wetting behavior, bio-corrosion resistance to SBF solution, and antibacterial performances against S. aureus. The results show that the refinement in grain size and presence of Ti2Cu and TiCu2 subjected to LSP enhanced the wettability of the surface. The application of LSP treatment is seen to significantly improve the surface corrosion resistance, reduce the adhesion of bacteria and in turn enhance the antibacterial properties of the wrought Ti-3Cu alloys.

Characterization of the Influence of Bovine Serum Albumin (BSA) upon the Electronic Properties and Surface Topography of a Ti-3Cu Biomedical Alloy by Mott-Schottky Analysis (MSA) and Atomic Force Microscopy (AFM)

The electronic characteristics, surface topography, and surface roughness of a Ti-3Cu alloy were investigated in phosphate buffered saline (PBS) containing bovine serum albumin (BSA) at 37 °C and pH 7.4 ± 0.2 by Mott-Schottky analysis (MSA) and atomic force microscopy (AFM). The n-type oxide layer was produced on the Ti-3Cu alloy surface due to the formation of oxygen-deficient TiO2-x barrier layer with interstitial copper as As the serum-protein concentration increased from 1 g/L to 6 g/L in the phosphate buffered saline, the donor densities (ND) of the semiconducting oxide layer decreased. The accumulation of serum protein observed by atomic force microscopy became the driving force in the restructuring of the oxide film via chemisorption and caused a reduction in the donor densities. The change in the magnitude of the nano-roughness suggested chemisorption which is beneficial for the osseointegration of Ti-3Cu implants.

Enhancing the Antibacterial Properties and Biocompatibility of Ti-Cu Alloy by Roughening and Anodic Oxidation

Although Ti-Cu alloys have been shown to possess good antibacterial properties, they are still biologically inert. In this study, sandblasting and acid etching combined with anodic oxidation were applied to roughen the surface as well as to form a TiO2/CuO/Cu2O composite film, which would benefit both the antibacterial properties and the biocompatibility. The surface morphology, the phase composition, and the physicochemical properties were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Electrochemical testing and inductively coupled plasma spectrometry (ICP) were used to determine the corrosion resistance and Cu ion release, the plate counting method was used to evaluate the antibacterial performance, and the CCK-8 method was used to evaluate the cytocompatibility. It was revealed that a rough surface with densely porous double layer composed of TiO2/CuO/Cu2O was produced on Ti-Cu alloy surface after the combined surface modification, which enhanced the corrosion resistance significantly. The plate counting results demonstrated that the modified sample had strong long-term antibacterial performance (antibacterial rate > 99%), which was attributed to the formation of TiO2/CuO/Cu2O composite film. The cell compatibility evaluation results indicated that the surface modification improved the cytocompatibility. It was demonstrated that the combined modification provided very strong antibacterial ability and good cytocompatiblity, potentially making it a good candidate surface modification technique for Ti-Cu alloy for biomedical applications.

3D printed Ti-5Cu alloy accelerates osteogenic differentiation of MC3T3-E1 cells by stimulating the M2 phenotype polarization of macrophages.

Ti-5Cu alloy has been proved to have excellent mechanical properties and cell compatibility and has certain antibacterial properties due to the addition of Cu. However, there are few studies on the effects of Ti-5Cu alloy on macrophage polarization and immune-related bone formation. In this study, we prepared Ti-5Cu alloy by three-dimensional printing technology and found that Ti-5Cu alloy presented a much smoother surface compared with Ti. In addition, the CCK-8 results indicated the Ti-5Cu alloy had no cytotoxicity to RAW264.7 cells by co-culture. The results of inductively coupled plasma mass spectrometry showed that the concentration of Cu2+ was 0.133 mg/L after 7 days of co-culture, and the CCK-8 results proved that Cu2+ had no cytotoxicity to RAW264.7 at this concentration. Then, we studied the effects of Ti-5Cu alloy on macrophage polarization; it was shown that the Ti-5Cu alloy is more prone to modulate the RAW264.7 polarization towards the M2 phenotype and the conditioned medium derived from Ti-5Cu alloy significantly promoted the proliferation and osteogenic differentiation of MC3T3-E1 cells. However, when the expression of Oncostatin M (OSM) gene of RAW264.7 was knocked down, the osteogenic differentiation of MC3T3-E1 cells was decreased. This suggests that the OSM secreted by RAW264.7 co-cultured with Ti-5Cu alloy could accelerate the osteogenic differentiation of MC3T3-E1 cells by acting on OSMR/gp130 receptors.

Microstructure, mechanical and tribological properties of a Ti-5Cu alloy and a B4C/Ti-5Cu in situ composite fabricated by laser powder bed fusion

Both a novel Ti-5Cu alloy (in wt%) and a Ti-5Cu in situ composite containing 1 wt% B 4 C were fabricated by laser powder bed fusion, and their microstructures, mechanical and tribological properties were systematically investigated. The microstructure of the Ti-5Cu was mainly composed of α Ti laths, Ti 2 Cu and retained β phases, while the B 4 C/Ti-5Cu composite was composed of α Ti laths, Ti 2 Cu, TiC, TiB and TiB 2 phases. Both the Cu and B 4 C additions promoted a transition from columnar to equiaxed grains for prior-β and α phases. The B 4 C/Ti-5Cu composite was found to have a higher hardness (467 HV) than the Ti-5Cu (417 HV). Further, the composite exhibits a yield strength of 1100 MPa and an ultimate tensile strength of 1250 MPa. Values which are higher than those of the Ti-5Cu that exhibits a yield strength of 750 MPa and an ultimate tensile strength of 900 MPa. However, this strength increase comes at the expense of a reduction in elongation to failure from 6.2% to 1.5%. Even though the composite is significantly stronger, the two materials exhibited very similar wear rates ( ω B4C/Ti-5Cu = 4.95 × 10 −4 mm 3 N −1 m −1 and ω Ti-5Cu = 4.85 × 10 −4 mm 3 N −1 m −1 ). • The SLMed Ti-5Cu was mainly composed of α Ti laths, Ti 2 Cu and retained β phases. • The SLMed B 4 C/Ti-5Cu composite was composed of α Ti laths, Ti 2 Cu, TiC, TiB and TiB 2 phases. • Both the addition of Cu and B 4 C can refine the grain and promote columnar to equiaxed transition of prior-β phase. • The SLMed Ti-5Cu exhibit a strong combination of hardness, tensile properties and wear resistance. • Although the composite is significantly stronger owing to the addition of B 4 C, the two materials exhibited very similar wear rates.

A method for the preparation of spherical titanium powder for additive manufacturing

In this work, a new method was designed and developed to produce spherical Ti powder for additive manufacturing (AM) process. In this method, copper was introduced to form Ti-Cu alloy with a low melting point, and spherical Ti powder was prepared by combining with several low-cost processing techniques, including solid-liquid interface dewetting spheroidization, dealloying, sintering and de‑oxygenation processes. The spherical Ti powder prepared by this method shows a low oxygen content (<0.1 wt%), and the particle size was controlled between 15 and 75 μm. Compared with the current mature technology of the preparation of spherical titanium powder, this method provideds unique advantages during the preparation of small-sized spherical Ti powder (<30 μm), which meets the requirements of high-quality AM technology. • A new method was designed and developed to produce spherical Ti powder. • Techniques and raw materials are low cost. • Spherical Ti powder with controllable size distribution and low oxygen content can be produced.

Evaluation of inhibition effect on microbiologically influenced corrosion of Ti-5Cu alloy against marine Bacillus vietnamensis biofilm

Titanium is highly susceptible to biofouling due to the poor toxicity and excellent biocompatibility. Microbiologically influenced corrosion of cp-Ti induced by Bacillus vietnamensis and the inhibition effect of Ti-5Cu alloy were evaluated using various electrochemical techniques and surface analyses. Electrochemical results revealed that, cp-Ti and Ti-5Cu alloy exhibited excellent passivation in the sterile medium. In biotic medium, however, attachment of B. vietnamensis biofilm to surface of cp-Ti accelerated the active dissolution and poisons repassivation. In contrast, cells adhered preferentially as a form of discrete colonies on Ti2Cu intermetallic phases. Release of Cu2+ ions induced damage in morphology of B. vietnamensis cells resulting in relative resistance to pitting corrosion estimated by 3.1 ± 0.6 µm and 2.0 ± 0.4 µm for cp-Ti and Ti-5Cu alloy, respectively.