Ti2Cu Intermetallic Compounds Research Articles

Enhancing fine-scale α phase precipitation and mechanical behavior by addition of Cu to metastable β Ti-5553 alloy

Metastable β Ti alloys in the β quenched condition exhibit relatively low mechanical strength. Aging heat treatment can improve mechanical strength because of controlled α phase precipitation into the β matrix. This study aimed to examine the aging response of a β quenched Cu-modified Ti-5553 alloy, α phase precipitation therein, and the resulting mechanical behavior. It was found that Cu addition resulted in the precipitation of a nanometric Ti2Cu intermetallic compound, which upon aging, affected α phase precipitation and therefore increased the ultimate tensile strength from 1147 to 1222 MPa at the expense of ductility.

Effect of phase conditions on tensile and antibacterial properties of Ti-Cu alloys with Ti2Cu intermetallic compound

In this study, the effect of phase conditions on the tensile behaviors of Ti-Cu alloys with Cu contents of 0, 10, 20, and 30 wt% is investigated by controlling the annealing temperature. An in-depth characterization of the alloy microstructure is performed using scanning electron microscopy and transmission electron microscopy. The results suggest that the mechanical properties of the Ti-Cu alloys are strongly affected by the Cu content in α lath, which is dependent on the volume of Ti2Cu rather than Ti2Cu itself. A high volume of Ti2Cu reduces the Cu content in α lath, resulting in high elongation and low strength. Ti2Cu has superior antibacterial properties when compared with that of the Cu-supersaturated α lath. This study provides new insights into the design of Ti-Cu alloys for application as a biomaterial.

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.

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.

Copper Deposition from Its Sulfate Solution onto Titanium Powder with the Simultaneous Mechanical Activation of the Mixture

To fabricate Cu–Ti composite particles, the method of copper deposition from its sulfate solution on titanium powder particles with the simultaneous mechanical activation (MA) of the mixture in an AGO‑2 planetary ball mill for 5 min is used. The CuSO4 ⋅ 5H2O concentration in solutions is 10 and 16%, which provides molar ratio Cu/Ti = 0.85 and 1.36, respectively, with the complete reduction of copper. The rapid reduction of copper in the form of highly dispersed partially amorphized powder occurs during MA, and composite particles with a thin laminate structure and high reaction ability are formed. Prepared composites are rinsed and stored in argon because reduced copper possesses high activity and rapidly oxidizes in air to oxide Cu2O. After drying, the additional MA of the mixture is performed for 5 min. Pellets 3 mm in diameter and up to 1.5 mm in height are compacted from prepared powders and heated in argon to 700–1200°C. An intense reaction with heat liberation (heat explosion) and the formation of TiCu, Ti2Cu3, and Ti2Cu intermetallic compounds starts upon sample heating. The critical inflammation temperature for composite powders formed by MA with simultaneous copper deposition from the solution is 480°C, which is 400°C below the inflammation temperature of the usual powder mixture of titanium and copper. The alloy has a dendritic structure at a heating temperature close to the melting point, while, if it is exceeded by more than 100°C, the phase distribution in the alloys becomes more uniform and their size decreases.

Characteristics of novel Ti–10Mo-xCu alloy by powder metallurgy for potential biomedical implant applications

When biomaterials are implanted in the human body, the surfaces of the implants become favorable sites for microbial adhesion and biofilm formation, causing peri-implant infection which frequently results in the failure of prosthetics and revision surgery. Ti–Mo alloy is one of the commonly used implant materials for load-bearing bone replacement, and the prevention of infection of Ti–Mo implants is therefore crucial. In this study, bacterial inhibitory copper (Cu) was added to Ti–Mo matrix to develop a novel Ti–Mo–Cu alloy with bacterial inhibitory property. The effects of Cu content on microstructure, tensile properties, cytocompatibility, and bacterial inhibitory ability of Ti–Mo–Cu alloy were systematically investigated. Results revealed that Ti–10Mo–1Cu alloy consisted of α and β phases, while there were a few Ti2Cu intermetallic compounds existed for Ti–10Mo–3Cu and Ti–10Mo–5Cu alloys, in addition to α and β phases. The tensile strength of Ti–10Mo-xCu alloy increased with Cu content while elongation decreased. Ti–10Mo–3Cu alloy exhibited an optimal tensile strength of 1098.1 MPa and elongation of 5.2%. Cytocompatibility study indicated that none of the Ti–10Mo-xCu alloys had a negative effect on MC3T3-E1 cell proliferation. Bacterial inhibitory rates against S. aureus and E. coli increased with the increase in Cu content of Ti–10Mo-xCu alloy, within the ranges of 20–60% and 15–50%, respectively. Taken together, this study suggests that Ti–10Mo–3Cu alloy with high strength, acceptable elongation, excellent cytocompatibility, and the bacterial inhibitory property is a promising candidate for biomedical implant applications.

Microstructure and shear strength of ZrB2[sbnd]SiC/Ti[sbnd]6Al[sbnd]4V joint by TiCuZrNi with Cu foam

In this paper, brazing behaviors between ZrB2SiC and Ti6Al4V by Cu foam interlayer were studied. The microstructure, formation mechanism, mechanical property and fracture surface of the joints were systematically studied. The results showed that the phases in the joints were α+β-Ti, TiCu, Ti2Cu, Cu(s, s), TiC, TiB2 and Ti3SiC2. An optimum shear strength reached up to 435 MPa at a brazing temperature of 910 °C and holding time of 20 min. Such a shear strength was 90 MPa higher than the one without the Cu foam. The obtained high shear strength of joint was discussed from microstructure and residual stress. With the increase of brazing time, Cu(s,s) gradually disappeared and the content of Ti2Cu intermetallic compound increased, which was harmful for the joint. Furthermore, the residual stress of joint with Cu foam was calculated to be 324 MPa, lower than the one without Cu foam interlayer.

Martensitic Transformation and Plastic Deformation of TiCuNiZr-Based Bulk Metallic Glass Composites

In this study, the microstructural evolution and mechanical properties of TiCuNiZr-based bulk metallic glass (BMGs) composites were systematically investigated in order to optimize both the strength and the ductility of BMGs. By tailoring the glass-forming compositions, TiCuNiZr-based BMG composites with different volume fractions of B2 (Ti,Zr)(Cu,Ni) crystals precipitating in the glassy matrix exhibit not only macroscopic ductility but also high strength as well as work-hardening, which is due to the formation of multiple shear bands and martensitic transformation during deformation. Optimized mechanical properties can be achieved when the crystalline volume fraction is at least higher than 44 vol. %, which is attributed to the sizeable difference between Young’s moduli of the B2 (Ti,Zr)(Cu,Ni) crystals and the glassy matrix, and the precipitation of Ti2Cu intermetallic compounds at the B2 crystal boundaries. Our study provides a complementary understanding of how to tailor mechanical properties of TiCu-based BMG composites.

Study of TLP bonding of Ti-6Al-4V alloy produced by vacuum plasma spray forming and forging

Due to the nature of the near-net-shape formed of Ti-6Al-4V alloy produced by vacuum plasma spray forming (VPSF), post-deposition heat treatment is necessary to achieve to the superior mechanical and physical properties. In this study, transient liquid phase (TLP) bonding of VPSF and forging Ti-6Al-4V alloy were investigated. Simultaneous joining process under equi-axed α phase heat treatment cycle was performed to achieve to a suitable microstructure and mechanical properties of both bonding area and parent metal. Different thicknesses of 2, 5, 10, and 25μm copper interlayer were used and the effect of the interlayer thickness was evaluated. Results showed that the joint region was wider in the TLP bonded VPSF alloy compared to the forged alloy under the same bonding conditions because of the higher diffusion rates in the VPSF alloy. The highest bonding shear strength was achieved for 2μm interlayer thickness. It was 452 and 492MPa for the TLP bonded VPSF and forged alloy, respectively. Increasing the interlayer thickness resulted in decreasing the bonding strength and increasing the hardness of the joint area due to the existence of Ti2Cu intermetallic compounds. The fracture analysis showed the brittle behavior due to the existence of the intermetallic compounds.

Conjugated precipitation of twin-related α and Ti2Cu phases in a Ti–25V–3Cu alloy

The formation of conjugated precipitates in a ternary Ti–25V–3Cu (wt.%) (Ti–24.4V–2.3Cu (at.%)) alloy subjected to isothermal aging at 500°C was investigated in this study. X-ray diffraction confirms that the equilibrium precipitates in the alloy are hexagonal α phase and body-centered-tetragonal (bct) Ti2Cu intermetallic compound. These precipitates are composed of two geometrically symmetrical components, which are verified by transmission electron microscopy (TEM) to be twin-related variants of α and Ti2Cu phases. Atomic-level characterizations incorporating high-resolution TEM and atom probe tomography were used to investigate the early-stage nucleation process of the precipitates. The results reveal that precipitation occurs heterogeneously on plate-like (or disc-like) metastable Cu-enriched GP zones that preferentially inhabit {110}β planes. Crystallographic orientation analyses suggest that the Ti2Cu phase is related to the matrix via a definite orientation relationship of (01¯3)Ti2Cu‖(011)β and [100]Ti2Cu‖[100]β, while the growth of the α phase is governed by the Potter’s OR such that (11¯01)α‖(011)β and [112¯0]α‖[11¯1]β. (01¯3)Ti2Cu and (11¯01)α are the twin planes of the respective phases. In spite of highly distinct crystal structures, the conjugated α and Ti2Cu phases attain a nearly perfect lattice correspondence along certain crystallographic planes, which results in a low interfacial energy configuration and favours the co-development of these phases.

Study on antibacterial activity and cytocompatibility of Ti–6Al–4V–5Cu alloy

A new biomedical Ti–6Al–4V–5Cu alloy with antibacterial function was developed by proper addition of copper (Cu) into Ti based alloy in this study. The microstructure, antibacterial activity and cytotoxicity of this Cu bearing titanium alloy were studied. It was found that the microstructure of Ti–6Al–4V–5Cu alloy consisted of α phase, β phase and Ti2Cu intermetallic compound, which could obtain a considerable antibacterial ability and inhibit the formation of bacterial biofilm through trace release of cupric ions from its surface. The cytotoxicity evaluation demonstrated that Ti–6Al–4V alloy played no toxic effect on the viability of MC3T3-E1 cells, showing a satisfied biocompatibility.

CuTiNiZrV Amorphous Alloy Foils for Vacuum Brazing of TiAl Alloy to 40Cr Steel

Vacuum brazing of TiAl alloy to 40Cr steel sheets was conducted with newly developed CuTiNiZrV amorphous foils. It was found that a diffusion layer, filler metal and reaction layer existed in the brazed seam. The diffusion layer in the joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25 (at.%) foil was flat and thin, containing Ti19Al6 and Ti2Cu intermetallic compounds; however, the diffusion layer brazed with Cu37.5Ti25Ni12.5Zr12.5V12.5 foil was uneven with bulges, consisting of essentially Ti-based solute solution. The foil with 12.5 at.% V showed inferior spreadability compared to that with 6.25 at.% V at brazing temperature. However, fracture happened along the diffusion layer with 6.25 at.% V foil due to the formation of brittle intermetallic phases, but the joints brazed with 12.5 at.% V foil failed through the TiAl substrate. These results show that designing amorphous alloy with less Ti and more V for brazing TiAl alloy to steel is appropriate.

Research on Interface Structure and Fracture Mechanism of Diffusion Bonding of Titanium Alloy/Cu/Stainless Steel

Using analysis methods of stretching test，SEM，EDS and microhardness test to investigate and research the mechanical properties, the fracture mechanism，the reacting phases are produced and the distribution range of vacuum diffusion bonding joints of Ti-6Al-4V/Cu/304. The results show that when bonding pressure is 5.0 MPa, the tensile strenght of the joint increases at first, but decreases with the increasing of bonding temperature and time, When bonding temperature is 1223K, bonding time is 3.6ks, there is a maximum tensile strength that is 163 Mpa. However, it will be disadvantageous to the performance of the joints, when bonding temperature and time extended overly. Using Copper foil as the interlayer, the intermetallic compounds did not generate in interface of Cu/304，Therefore, it formed multi-phase transition organizations by solid solution, intermetallic compounds in interface of Titanium alloy/Cu，such as TixCuy, TixFey and so on. The effect of TixCuy on strength of the joints is slightly larger than TixFey compound. The fracture mainly happened in the titanium alloy side Ti2Cu intermetallic compound in region Ⅱfor the source dehiscence, developping inⅡ-Ⅲ area junction weak intermetallic compounds of diffusion layer. It is brittle fracture. Therefore, it is the main way to improve the joint strength by improving the interface structure of titanium alloy/Cu side.

Corrosion resistance of Ti-Cu alloy

to investigate the corrosion behavior of Ti-Cu alloy in 0.9%NaCl solution and in acidified 0.9%NaCl solution. the microstructure of Ti-Cu alloys were characterized by means of X-ray diffraction (XRD). The electrochemical behavior of Ti-Cu alloy in two solutions (namely 0.9%NaCl solution and acidified 0.9%NaCl solution) was tested. Commercial pure Ti and 316L stainless steel were used as control. Ti-Cu alloys were composed by α-Ti and Ti(2)Cu intermetallic compound. After 3500 s immersion, the open circuit potential (OCP) values of pure Ti, Ti-5Cu alloy and Ti-10Cu alloy in 0.9% NaCl solution were -188, -181 and -173 mV, respectively. In 0.9% NaCl solution with lactic acid added, the OCP values were -143, -158 and -109 mV, respectively. In potentiodynamic polarization tests, the passive current densities of pure Ti and Ti-5Cu alloys were about 20 µA/cm(2). However, 316L stainless steel experienced pitting corrosion. it was possible to establish the following relation for their corrosion resistances: pure Ti≈Ti-5Cu > Ti-10Cu > 316L stainless steel. The addition of lactic acid in the solution did not compromise the corrosion resistance of Ti-Cu alloys.

Mechanical behavior and deformation mechanisms of Ti–2.5Cu alloy reinforced by nano-scale precipitates at 293 and 77 K

Nano-scale precipitates were obtained in Ti–2.5Cu alloy after solution and aging treatment, and the precipitates were determined to be Ti 2Cu intermetallic compound and arrange along three directions [ 1 ̄ 2 2 ̄ ], [ 2 1 ̄ 1 ] and [ 2 1 1 ̄ ]. Tensile tests and low-cycle fatigue tests were conducted at 293 and 77 K. The results show that Ti–2.5Cu alloy possesses higher ductility and longer low-cycle fatigue life at 77 K than at 293 K, which can be interpreted by the model of twinning induced plasticity (TWIP). The microstructures indicate that slipping is predominant deformation mode at 293 K, and twinning becomes more active at lower temperature or under push–pull cyclic loading. The precipitates hinder the movement of dislocation obviously, while have little effect on twinning process. There are five types of twins identified in deformation of Ti–2.5Cu alloy reinforced by nano-scale Ti 2Cu intermetallic compound, which are { 1 1 2 ̄ 4 }, { 1 0 1 ̄ 1 }, { 1 0 1 ̄ 2 }, { 1 1 2 ̄ 2 } and { 1 1 2 ̄ 1 } twins.