Ternary Ti Research Articles

Characterization and first principle study of ball milled Ti–Ni with Mg doping as hydrogen storage alloy

Microstructures, electrochemical properties of Ti–Ni and ternary Ti–Ni–Mg alloy were studied after they had been submitted to high-energy ball milling. Influence of milling time and Mg addition on the microstructures of the mechanically milled Ti–Ni alloys was investigated by XRD, SEM. Cycling performances of the electrodes prepared by the milled powders were measured under galvanostatic conditions. It is found that the binary Ti–Ni alloy undergoes a refinement, dynamical recrystallization and amorphization process. With doping of Mg to the starting Ti–Ni powders, an FCC Ti–Mg structure was detected along with the main TiNi BCC phase. First principle calculation was applied to compare the thermodynamic stabilities of several binary alloys involving Ti, Ni and Mg. It was decided that the final product of milling Mg doped Ti–Ni contains an FCC structured TiMg3 phase, which damages electrochemical performance in general as a result of coating effect on the TiNi phase.

Vascular endothelial cell compatibility of superhard ternary Ti–Si–N coatings with different Si contents

Superhard ternary Ti–Si–N coatings with different Si atomic concentrations are deposited on titanium alloy substrates by arc-enhanced magnetron sputtering (AEMS) and the vascular endothelial cell compatibility is studied. In vitro studies show that the surface hydrophilicity and hemolysis are about the same as those of the titanium alloy control and platelet adhesion and protein adsorption tests suggest a close relationship between the surface energy and blood compatibility. Endothelial cells cultures reveal better proliferation and anti-platelet adhesion on the coatings compared to the titanium alloy control and the Ti–Si–N coating with 20 at% Si exhibits excellent endothelialization.

O181 Projected benefits of a home-based approach to chronic heart failure management: Long-term data from the multicentre Which Intervention is most cost-effective and Consumer friendly in reducing Hospital stay Trial

Hard coatings based on ternary Ti–Al–N and Cr–Al–N are commercial products currently employed in many industrial applications due to their outstanding chemical and physical properties, including high hardness and toughness and thermal as well as chemical stability. In this chapter the current understanding of mechanisms relevant for the thermal and chemical stability of these coating systems will be summarized based on state-of-the-art experimental and computational data.Synthesized by low-temperature (substrate temperatures below 500 °C) plasma-assisted vapor deposition (PVD) techniques, ternary Ti1−xAlxN, Cr1−xAlxN, and related coatings form metastable solid solutions. Depending on the chemical composition (and the deposition parameters used, like substrate temperature, gas pressure, and ion bombardment), the coatings crystallize in a face centered cubic (fcc) NaCl-type (c) or a hexagonal close packed (hcp) wurtzite-type (w) phase. For the main engineering applications, the cubic modification is preferred due to the superior mechanical, tribological, and oxidation properties. For example, the hardness of as-deposited c-Ti1−xAlxN and c-Cr1−xAlxN coatings, with AlN content (x) close to its metastable cubic solubility limit of x ∼ 0.7, can be as high as 37 and 30 GPa, respectively. During thermal treatments above the deposition temperature (e.g., during cutting application), the coatings undergo various processes to reach equilibrium. While for single-phase cubic Ti1−xAlxN the decomposition into the stable phases c-TiN and w-AlN occurs across the formation of cubic Al-rich and Ti-rich domains, the decomposition of Cr1−xAlxN is driven by nucleation and growth of w-AlN as well as by the release of N2 starting at temperatures around 1000 °C. The combination of experimental (e.g., x-ray diffractometry, calorimetry, nanoindentation, scanning and transmission electron microscopy, and atom probe tomography) with computational (e.g., density functional theory and continuum mechanics) studies allows for identifying, describing, and understanding the mechanisms and processes that govern the thermally induced decomposition. Thermal stability is discussed for Ti1−xAlxN-based coating systems, while chemical stability is analyzed for Cr1−xAlxN-based coating systems. Furthermore, the influence of alloying elements such as Y, Nb, Ta, Zr, and Hf on the phase formation, structure, mechanical, and thermal properties of these ternary Ti1−xAlxN and Cr1−xAlxN coatings is discussed.

Phase Equilibria During Solidification in the Ti–TiAl–DyAl2–Dy Region of the Ti–Dy–Al System

Phase equilibria during solidification in the Ti–TiAl–DyAl2–Dy region of the Ti–Dy–Al system are studied by differential thermal analysis, X-ray diffraction, metallography, and electron microprobe analysis. The liquidus and solidus surfaces, vertical sections, and reaction scheme in the solidification range are presented. No ternary compounds are found in the studied composition range. It is shown that DyAl2 undergoes polymorphic transformation at ~1200°C. The αl and α2 phases that coexist only with solid phases in the binary Ti–Al system participate in equilibria with the liquid phase in the ternary Ti–Dy–Al system. The liquidus surface is characterized by the primary solidification fields of the phases based on βTi (β), high-temperature αTi (αh), lowtemperature αTi (αl), Ti3Al (α2), TiAl (γ), Dy2Al, Dy3Al2, DyAl, βDyAl2, αDyAl2, βDy, and αDy. The solidus surface has elven three-phase fields: β + (βDyAl2) + αl, (βDyAl2) + αl + α2, β + αh + (βDyAl2), αh + γ + (βDyAl2), (βDyAl2) + α2 + (αDyAl2), (DyAl) + (Dy3Al2) + (αDyAl2), (αDy) + β + αl, (DyAl2) + α2 + (Dy3Al2), (Dy3Al2) + α2 + (Dy2Al), α2 + αl + (Dy2Al), and αl + (αDy) + (Dy2Al). The first two fields result from invariant four-phase peritectic reactions, LP1 + β + (DyAl2) ⇄ αl and LP2 + αl + (βDyAl2) ⇄ α2 proceeding at 1130 ± 5°C and 1180 ± 7°C, respectively. The next eight three-phase fields result from invariant four-phase transition reactions: LU1 + β ⇄ αh + (βDyAl2) at 1325 ± 8°C, LU2 + αh ⇄ γ + (βDyAl2) at 1260°C, LU3 + (βDyAl2) ⇄ α2 + (αDyAl2) at 1060 ± 4°C, LU4 + (DyAl) ⇄ (Dy3Al2) + (αDyAl2) at 1010 ± 9°C, LU5 + (αDy) ⇄ β + αl at 970 ± 4°C, LU6 + (αDyAl2) ⇄ α2 + (Dy3Al2) at 960 ± 8°C, LU7 + (Dy3Al2) ⇄ α2 + (Dy2Al) at 955 ± 16°C, and LU8 + α2 ⇄ αl + (Dy2Al) at ~930°C. The three-phase αl + (αDy) + (Dy2Al) field results from an invariant eutectic process, LE ⇄ αl + (αDy) + (Dy2Al), at 910 ± 15°C. The two-phase region in the solidus surface has a temperature maximum at 1343 ± 5°C, corresponding to the invariant three-phase le1 ⇄ β + (βDyAl2) reaction.

Physical and tribological diagnostic of Ti-(Carbon Nitrides) and Ti-Nb-(Carbon Nitrides) coatings

Electrochemical, mechanical and tribological properties of Ti-C-N and Ti-Nb-C-N coatings deposited onto Si (100) and AISI 4140 steel substrates were determined in this work. Introduction of Nb in the ternary Ti C-N film was evaluated via quantitative elemental concentration depth profile by glow discharge optical emission spectroscopy (GDOES) and the morphology via scanning electron microscopy (SEM) were observed for the layers before the tests. The morphological surface was analyzed via AFM. Mechanical and tribological properties for both coatings were obtained by mean of nanoindentation measurements throughload versus displacement method, and scratch test using the critical load criterion, respectively. The failure modes from scratch test were observed via optical microscopy. Nanoindentation results reaching the elastic-plastic behavior of the TiCN and Ti-Nb-C-N coatings with inclusion of Nb (TiNbCN), indicated not only the hardness and elastic modulus but also the critical load for the adhesive failure increase when increasing r.f negative bias voltage. An improvement of hardness and critical load around 60% and 28% for TiCN as well as 26% and 31% for TiNbCN, respectively, was associated to an increasing in the r.f negative bias voltage from 0 V to -100 V.

Site occupation of Nb atoms in ternary Ni–Ti–Nb shape memory alloys

Site occupation of Nb atoms in ternary Ni–Ti–Nb shape memory alloys

On the faradaic selectivity and the role of surface inhomogeneity during the chlorine evolution reaction on ternary Ti-Ru-Ir mixed metal oxide electrocatalysts.

The faradaic selectivity of the chlorine evolution reaction (CER) and oxygen evolution reaction (OER) on the industrially important Ti-Ru-Ir mixed metal oxide is discussed. Absolute evolution rates as well as volume fractions of Cl2 and O2 were quantified using differential electrochemical mass spectrometry (DEMS), while the catalyst surface redox behavior was analyzed using cyclic voltammetry. The spatial inhomogeneity of the surface catalytic reaction rate was probed using Scanning Electrochemical Microscopy (SECM). Although the nature of the competition between electrochemical discharging of chloride ions and water molecules remains elusive on a molecular scale, new insights into the spatial reactivity distribution of the CER and OER were obtained. Oxidation of water is the initial step in corrosion and concomitant deactivation of the oxide electrodes; however, at the same time the nature of interaction between the oxide surface and water is used as a rational indicator of selectivity and catalytic activity. An experimental procedure was established that would allow the study of selectivity of a variety of different catalyst materials using polycrystalline electrode surfaces.

Effects of Mo content on microstructure and corrosion resistance of arc ion plated Ti–Mo–N films on 316L stainless steel as bipolar plates for polymer exchange membrane fuel cells

Bipolar plates are one of the most important components in PEMFC stack and have multiple functions, such as separators and current collectors, distributing reactions uniformly, and etc. Stainless steel is ideal candidate for bipolar plates owing to good thermal and electrical conductivity, good mechanical properties etc. However, stainless steel plate still cannot resist the corrosion of working condition. In this work, ternary Ti–Mo–N film was fabricated on 316L stainless steel (SS316L) as a surface modification layer to enhance the corrosion resistance. Effects of Mo content on the microstructure and corrosion resistance of Ti–Mo–N films are systematically investigated by altering sputtering current of the Mo target. XRD results reveal that the preferred orientation changes from [111] to [220] direction as Mo content in the film increases. The synthesized Ti–Mo–N films form a substitutional solid solution of (Ti, Mo)N where larger Mo atoms replace Ti in TiN crystal lattice. The TiN-coated SS316L sample shows the best corrosion resistance. While Mo content in the Ti–Mo–N films increases, the corrosion resistance gradually degrades. Compared with the uncoated samples, all the Ti–Mo–N film coated samples show enhanced corrosion resistance in simulated PEMFC working condition.

Modification of Structure and Properties of Titanium Surfaces During Formation of Silicides and Borides Initiated by High-Energy Treatment

An analysis of binary (Ti–Si, Ti–В, Si–B) and ternary (Ti–Si–B) phase states is made, their diagrams are presented, and a possibility for formation of a large number of metastable compounds is revealed. The latter are found to form as a result of application of non-equilibrium conditions in the course of material treatment with concentrated high-energy flows. Using an x-ray diffraction analysis and electron-diffraction microscopy, the phase composition of the surface layer of technical-grade titanium (VT1-0) treated by concentrated energy flows (irradiation with plasma from electrical wire explosion and high-intensity pulsed electron beam) is investigated.

Deformation-induced changeable Young's modulus with high strength in β-type Ti–Cr–O alloys for spinal fixture

In order to meet the requirements of the patients and surgeons simultaneously for spinal fixation applications, a novel biomedical alloy with a changeable Young's modulus, that is, with a low Young's modulus to prevent the stress-shielding effect for patients and a high Young's modulus to suppress springback for surgeons, was developed. In this study, the chromium and oxygen contents in ternary Ti(11, 12mass%)Cr–(0.2, 0.4, 0.6mass%)O alloys were optimized in order to achieve a changeable Young's modulus via deformation-induced ω-phase transformation with good mechanical properties.The Young's moduli of all the examined alloys increase after cold rolling, which is attributed to the deformation-induced ω-phase transformation. This transformation is suppressed by oxygen but enhanced with lower chromium content, which is related to the β(bcc)-lattice stability. Among the examined alloys, the Ti–11Cr–0.2O alloy shows a low Young's modulus of less than 80GPa in the solution-treated (ST) condition and a high Young's modulus of more than 90GPa in the cold rolled (CR) condition. The Ti–11Cr–0.2O alloy also exhibits a high tensile strength, above 1000MPa, with an acceptable elongation of ~12% in the ST condition. Furthermore, the Ti–11Cr–0.2O alloy exhibits minimal springback. This value of springback is the closest to that of Ti64 ELI alloy among the compared alloys. Therefore, the Ti–11Cr–0.2O alloy, which has a good balance between large changeable Young's modulus, high tensile strength, good plasticity, and minimal springback, is considered to be a potential candidate for spinal fixation applications.

Effect of Chromium and Niobium on the Kinetics of Synthesis of Titanium Aluminide

The kinetics of the reaction of synthesis of titanium aluminide from binary (Ti – 48% Al), ternary (Ti – 48% Al – 2% Cr, Ti – 48% Al – 2% Nb) and quaternary (Ti – 48% Al – 2% Cr – 2% Nb) mixtures of elementary powders is studied. Differential scanning calorimetry in heating of the powder mixtures is used to determine the temperature and heat of formation of titanium aluminides and the kinetic parameter and activation energy in the Johnson – Mehl – Avrami equation.

Pumping properties of Ti–Zr–Hf–V non-evaporable getter coating

The ternary Ti–Zr–V non-evaporable getter coating is widely used on accelerator vacuum chambers in many accelerator centres. This coating can be activated at 180 °C for 24 h and has well repeatable pumping characteristics. A new quaternary Ti–Zr–Hf–V coating was deposited onto inner surface of stainless steel tubular samples. This coating can be activated at lower temperature of 150–160 °C for 24 h and has better pumping characteristics. Alike our earlier results with Ti–Zr–V coating, the Ti–Zr–Hf–V coating made with an alloy target allows to reach higher pumping sticking probabilities and capacity than one made with a twisted wire targets.

Isothermal sections at 1400, 1100 and 900°C of the Ti–Dy–Sn system below 40at.% Sn

Abstract By the methods of X-ray diffraction, SEM and electron probe microanalysis, phase equilibria in the Ti–Dy–Sn system below 40 at.% Sn at temperatures 1400, 1100 and 900 °C were studied. The isothermal sections at 1400, 1100 and 900 °C were constructed. It was shown that the ternary compound Ti 4.2−4.3 Dy 0.8−0.7 Sn ⩽ 3 ( τ ) is stable at these temperatures. At 1400 °C the liquid phase is present in the system. The isothermal section at this temperature is characterized by the three-phase regions L + (βTi) + (Dy 5 Sn 3 ), (βTi) + (Тi 3 Sn) + (Dy 5 Sn 3 ), (Ti 3 Sn) + τ + (Dy 5 Sn 3 ), (Ti 3 Sn) + τ + (Ti 2 Sn) and (Ti 2 Sn) + τ + (Ti 5 Sn 3 ) and appropriate two-phase fields. At 1100 and 900 °C the liquid phase is absent, instead the three-phase field (βTi) + (αDy) + (Dy 5 Sn 3 ) appears. Other three-phase fields exist at all the temperatures studied. The isothermal sections at 1100 and 900 °C by their character are similar to the solidus surface.

Thermodynamic analysis of Ti–Al–C intermetallics formation by mechanical alloying

In the present study the behavior of Ti–Al–C ternary system is investigated during mechanical alloying. The mixture of Ti, Al and C powders was used with initial stoichiometric composition of Ti3AlC2. X-ray diffraction (XRD) was used to characterize the milled powders and a thermodynamic analysis of the process was then carried out using Miedema model. This thermodynamic analysis showed that for all binary Ti–C, Al–C, Ti–Al systems and ternary Ti–Al–C systems, among all compositions, the thermodynamic driving force for intermetallic phase formation is much greater when compared with the formation of solid solutions or amorphous phases. Finally the reactions that are feasible to occur during mechanical alloying (MA) of Ti–Al–C system were investigated thermodynamically.

Evaluation of the microstructural, mechanical and anti‐corrosive properties of a new ternary Ti–15Zr–5Nb alloy in simulated oral environment

A new ternary Ti–15Zr–5Nb alloy was elaborated with the aim to satisfy the most stringent requirements of a good implant material. The alloy has α + β bi‐phase microstructure (by XRD and optical microscopy) and presents a proper combination between Young's modulus, elasticity and good ultimate tensile strength and 0.2% yield strength (from stress–strain tensile curve), indicating a good suitability as implant material. Electrochemical behaviour in artificial Carter‐Brugirard saliva of different pH values (3.96, 7.84, and 9.11) and composition (un‐doped and doped with 0.05 M NaF) that simulate the severe functional conditions in the oral cavity was evaluated. All electrochemical parameters of the new alloy revealed more favourable values than those of the CP Ti and Ti–6Al–4V ELI alloy, showing a more compact, resistant passive film formed on the new alloy surface. The corrosion rates and corresponding ion release rates for the new Ti–15Zr–5Nb alloy exhibited very low values (hundreds of times smaller) in comparison with similar commercial biomaterials. Electrochemical impedance spectra distinguished bi‐layered passive film formed by inner, barrier layer and outer, porous layer. X‐ray photoelectron spectra and scanning electron microscopy (SEM) observations proved that in time, protective compounds were deposited from saliva on the alloy surface, enhancing its corrosion resistance.

On the mechanical properties of TiNb based alloys

A series of TiNb(Sn) alloys were synthesized by copper mold suction casting and subjected to different heat treatments (furnace cooling or water quenching). The microstructure, thermal and mechanical properties of the as-cast and heat treated samples were investigated. For the Ti–8.34at.% Nb alloy, the as-cast and water quenched samples possess martensitic α′′ phase at room temperature and compression tests of these samples show occurrence of shape memory effect. For β phase Ti–25.57at.% Nb alloys, stress-induced martensitic transformation was found during compression in the as-cast and water quenched samples. For the ternary Ti–25.05at.%Nb–2.04at.%Sn alloy, conventional linear elastic behavior was observed. It is shown that the addition of Sn increases the stability of the β phase. The Young’s moduli of these alloys were also measured by ultrasonic measurements. Water-quenched Ti–25.57at.%Nb alloy was found to exhibit the lowest Young’s modulus value. Sn addition has small impact on the Young’s moduli of the TiNb alloys.

Ternary Ti–Mo–Ni mixed oxide nanotube arrays as photoanode materials for efficient solar hydrogen production

To date, most studies on the fabrication and development of photoelectrodes for solar-fuel generation have been based on simple binary systems with limited success. However, ternary systems have not been explored extensively although they can offer more possibilities for band gap and band alignment tuning that allow the development of more efficient photoelectrochemical systems. Herein, we report on the growth of a novel ternary oxide photoanode material composed of self-ordered, vertically oriented nanotube arrays of titanium-molybdenum-nickel mixed oxide films via the anodization of a Ti-Mo-Ni alloy in an electrolyte solution of formamide containing NH4F at room temperature, followed by annealing in an air atmosphere. The nanostructure topology was found to depend on both the anodization time and the applied voltage. Our results demonstrate the ability to grow mixed oxide nanotube array films that are several microns thick. The Ti-Mo-Ni mixed oxide nanotube array films were utilized in solar-spectrum water photoelectrolysis, demonstrating a photocurrent density of 2.1 mA cm(-2) and a ∼10 fold increase in the photoconversion efficiency under AM 1.5 illumination (100 mW cm(-2), 1 M KOH) compared to pure TiO2 nanotubes fabricated under the same conditions. This enhancement in the photoconversion efficiency can be related to the synergistic effects of Ni and Mo alloying and the unique structural properties of the fabricated nanotube arrays.

Microstructure evolution and mechanical properties of Ti–B–N coatings deposited by plasma-enhanced chemical vapor deposition

Ternary Ti–B–N coatings were synthesized on AISI 304 and Si wafer by plasma-enhanced chemical vapor deposition (PECVD) technique using a gaseous mixture of TiCl4, BCl3, H2, N2, and Ar. By virtue of X-ray diffraction analysis, X-ray photoelectron spectroscopy, scanning electron microscope, and high-resolution transmission electron microscope, the influences of B content on the microstructure and properties of Ti–B–N coatings were investigated systematically. The results indicated that the microstructure and mechanical properties of Ti–B–N coatings largely depend on the transformation from FCC-TiN phase to HCP-TiB2 phase. With increasing B content and decreasing N content in the coatings, the coating microstructure evolves gradually from FCC-TiN/a-BN to HCP-TiB2/a-BN via FCC-TiN+HCP-TiB2/a-BN. The highest microhardness of about 34 GPa is achieved, which corresponds to the nanocomposite Ti–63%B–N (mole fraction) coating consisting of the HCP-TiB2 nano-crystallites and amorphous BN phase. The lowest friction-coefficient was observed for the nanocomposite Ti–41%B–N (mole fraction) coating consisting of the FCC-TiN nanocrystallites and amorphous BN phase.

Influence of equiatomic Zr/Nb substitution on superelastic behavior of Ti–Nb–Zr alloy

Based on a binary Ti–26Nb (at%) alloy, Ti–(26-z)at% Nb-(z)at% Zr (z=2, 6, 8 and 10) alloys via equiatomic substitution of Nb by Zr are formulated. Influence of equiatomic Zr/Nb substitution on microstructure evolution, mechanical properties and deformation mechanism of the superelastic Ti–Nb–Zr alloy are investigated. Experimental results show that the phase constitution is single β phase or β/ωath phase at 0<Zr/Nb<0.35 since the measured Ms temperature is maintained at around 250K. The two-phase microstructure consist of α″ martensite and β phase is obtained at Zr/Nb ratio>0.4 due to the attenuation of β stabilizing effect of Zr, which is related closely to the Nb content in ternary Ti–Nb–Zr alloys. The mechanism of the superelastic behavior alters gradually from reversible β/α″ martensitic transformation to rearrangement of pre-existing α″ martensites as a function of Zr/Nb ratio increase. At Zr/Nb=0.3, the alloy of corresponding composition exhibits the best superelasticity and combined mechanical performance. A coefficient of ΔT (ΔT=Tβ-Ms) is proposed to understand the experimental results by evaluating the β instability of Ti–Nb–Zr alloys.

Stress, phase stability and oxidation resistance of ternary Ti–Me–N (Me = Zr, Ta) hard coatings

In this work, we comparatively study the phase formation, stress development, thermal stability and oxidation resistance of two ternary transition metal nitride systems, namely Ti–Zr–N and Ti–Ta–N, in the whole compositional range. Thin films, with thickness up to 300nm, were synthesized by reactive magnetron sputter-deposition in Ar+N2 plasma discharges at 300°C from elemental metallic targets. The energy distribution of energetic species is considered based on Monte-Carlo simulations (SRIM+SIMTRA codes). The origin of stress build-up during growth is addressed by combining in situ wafer curvature and ex situ X-ray diffraction (XRD) techniques. For as-deposited films, a unique dependence of growth morphology, grain size, preferred orientation and compressive stress evolutions on growth energetics is revealed, independently of the system. The phase stability upon vacuum and air annealing up to 850°C was followed using in situ temperature XRD, ex situ X-ray Photoelectron Spectroscopy and optical reflectivity, while the morphological evolution was characterized using field emission scanning electron microscopy.