Thick Titanium Research Articles

Microstructure Appearance of TC4 Titanium Alloy Welded Join by Pulsed Electron Beam

Study on microstructure appearance of 3 mm thick TC4 titanium alloy welded join by common electron beam and pulsed electron beam were carried out. Experimental results show that pulsed electron beam improved grain size and decreased the cooling velocity of weld metal by oscillation and fast cooling effect, the acicular martensite decomposes β phase and transforms to finer and more α′ phase, which shows an interwoven pattern.

Electromagnetic simulation of MXene-based plasmonic metamaterials with enhanced optical absorption

In this contribution we propose, design and numerically analyze a plasmonic metamaterial for enhanced optical absorption, based on 100 nm thick titanium carbide (Ti3C2Tx) MXene sheets. The analyzed metamaterial is built as a sandwich with a solid MXene bottom (ground) layer, a lossless dielectric middle layer and an MXene mesh top layer. The unit cell of the periodic top mesh consists of two crossed ultrathin MXene strips, each of them spreading its width in step-like increments towards the middle of the unit cell. This ensures position-variable width of the top surface apertures, resulting in a widening of the bandwidth of spectral dispersion of the scattering parameters of the obtained metamaterial. We utilize the finite element method to simulate the scattering parameters of the MXene-based metamaterial. We apply Drude–Lorentz model to derive our analytical expression for complex permittivity of Ti3C2Tx MXene based on experimental measurements. The described approach is general, since various alternative plasmonic materials can be utilized, including different MXenes, but other materials as well, such as graphene, metals and metal alloys, semiconductors, etc. The approach is applicable to various other nanoplasmonic structures. In this manner the available toolbox for plasmonics is extended and a new degree of design freedom ensured.

Microstructure and mechanical properties of dissimilar Ti/Nb/Cu/steel laser joints

The absence of intermetallic phases in Fe/Cu, Cu/Nb and Nb/Ti binary systems opens the possibility to obtain reliable joints between titanium alloys and steels by using a multimaterial copper/niobium insert. Continuous Yb:YAG laser welding of 1 mm thick titanium and 316L stainless steel plates through niobium/copper multimaterial insert was performed. The use of a 100 µm laser beam allowed producing isolated molten zones and thus completely avoiding the formation of brittle intermetallic phases, according to SEM and XRD analysis. The effect of energy per unit length applied to the niobium/copper welds on the mixing process and mechanical properties of the joints was investigated. A ductile fracture systematically occurred in the unmelted copper zone of the joints at maximal average UTS of 250 MPa.

The Effect of Layer Thicknesses in Hybrid Titanium-Carbon Laminates on Low-Velocity Impact Response.

The purpose of the work was the effect of metal volume fraction of fiber metal laminates on damage after dynamic loads based upon the example of innovative hybrid titanium–carbon composite laminates. The subject of the study was metal–fiber hybrid titanium–carbon composite laminates. Four types of hybrid titanium–carbon laminates were designed with various metal volume fraction coefficient but constant thickness. Based on the results, it can be stated that changes in the metal volume fraction coefficient in the range of 0.375–0.6 in constant thickness titanium–carbon composite laminates do not significantly affect their resistance to impacts in the energy range of 5–45 J. It was concluded that there were no significant differences in maximum force values, total contact time, and damage range. Some tendency towards a reduction in the energy accumulation capacity was observed with an increase in thickness of the metal part in relation to the total thickness of the laminate, especially in the lower impact energy range. This can result in the lower bending stiffness of laminates with lower metal content and potential elastic strain of the composite part before the initiation of the fiber damage process.

EXAFS of titanium LIII edge using a compact laboratory system based on a laser-plasma soft X-ray source

We present results of applying a compact laboratory system based on a laser-plasma soft X-ray (SXR) source to the extended X-ray absorption fine structure (EXAFS) spectroscopy of titanium in the vicinity of the LIII absorption edge. The source, operating with a plasma produced as a result of irradiation a krypton/helium double-stream gas-puff target, was optimized for an intense emission in the spectral range between 200 and 700 eV. A broad SXR spectrum and high photon flux are indispensable in the EXAFS studies. The experimental setup assured the simultaneous acquisition of both the reference and the absorption spectra. A grazing-incidence flat-field spectrometer was used to record the spectra. The absorption spectra of a thin (200-nm thick) titanium sample revealed the features in the EXAFS region allowing for quite accurate determination of the radial distances between the atoms. Results are in good agreement with the output of numerical modeling based on photoelectron wave function scattering and with the data reported for using a synchrotron source. This confirms the suitability of the source for using it in the standard EXAFS method.

Comparative study of in vitro apatite-forming abilities of highly ordered rutile nanorod arrays fabricated on cpTi and Ti6Al4V alloys

ABSTRACTThe surfaces of commercially available pure titanium (cpTi) and Ti6Al4V alloy specimens were modified to form highly ordered rutile nanorod arrays by chemical treatment and subsequent aging treatment. The densities of the rutile rods were (1.04 ± 0.06) ×103 and (0.70 ± 0.10) ×103 μm–2 for the cpTi and Ti6Al4V alloy specimens, respectively. Both the rutile nanorod arrays on the cpTi and Ti6Al4V alloy specimens deposited apatite particles when soaked in simulated body fluid (SBF) for one day. After soaking for various other periods, scanning electron microscopy images and thin-film X-ray diffraction patterns of these specimens showed that the cpTi specimens exhibited a superior rate of apatite nucleation and favored the formation of numerous apatite particles with larger diameter. This superior apatite-forming ability of the cpTi specimens can be attributed to the dense, thick titania layers with higher rutile nanorod density on their surfaces.

Sol-Gel Fabricated Tio₂ Coating on Titanium Surface Promoted In Vitro Osteoblasts Differentiation.

Titanium has been used for biomedical devices due to its excellent biocompatibility, which is based partly on its 2-8 nm thick titanium oxide layer. However, the relatively poor surface hardness, wear resistance and metal release of these layers may cause some problems in clinical application. In this study, titanium surfaces were modified using a TiO₂ sol-gel coating, in order to improve surface properties and osteoblast function. No significant difference in surface roughness was observed between titanium and TiO₂ sol-gel discs. The surface of TiO₂ sol-gel discs possessed more wettability than titanium discs. The X-ray diffraction results showed amorphous TiO₂ phase on titanium discs, whereas TiO₂ sol-gel surfaces presented TiO₂ rutile and anatase phase. After 4 hours, the number of osteoblasts seeded on TiO₂ surface was significantly higher than those on titanium discs. The mRNA expression of bone sialoprotein and osteocalcin were also higher on day 5 and 7, respectively. Enzyme-linked immunosorbent assay(ELISA) analysis confirmed the increase of osteocalcin protein synthesis in osteoblasts grown on the TiO₂ sol-gel surface. Alizarin red-S staining showed higher amount of calcium deposition from osteoblasts cultured on TiO₂ surface than those on titanium discs at day 20. In conclusion, TiO₂ sol-gel coated-titanium could enhance osteoblasts differentiation and promote mineralization, indicating its potential in improving osseointegration for clinical application.

Ultrathin Chromia on a Hexagonally-Ordered d0 Ferromagnet: Evidence of Interfacial Exchange Bias at the Cr2O3/TiO2-x Interface.

Heterostructures consisting of 10 Å thick chromia films and 50 Å thick titania films display significant exchange bias at and above room temperature. Chromia films ∼10 Å thick were deposited by molecular beam epitaxy (MBE) of Cr at room temperature in ultrahigh vacuum on 50 Å thick TiO2-x(111) films (x < 0.3) also deposited epitaxially by MBE on Al2O3(0001). Cr deposition yields increased Ti(III) formation in the titania substrate and the formation of a Cr2O3 overlayer, without Cr/Ti interfacial mixing, as determined by in situ photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS). In situ low-energy electron diffraction (LEED) and XPS data indicate that the chromia overlayer is hexagonally ordered and ∼10 Å thick. Longitudinal and polar magneto-optic Kerr effect (MOKE) measurements at 285-315 K provide evidence of strong exchange bias between the boundary layer magnetization of chromia and the ferromagnetic substrate. These data demonstrate the robust room-temperature interaction of the boundary layer magnetization of a multiferroic antiferromagnet with a d0 ferromagnetic substrate.

Ultrashort Pulsed Laser Surface Patterning of Titanium to Improve Osseointegration of Dental Implants

Ultrashort pulsed direct laser interference patterning (DLIP) is used to generate hierarchical line‐like patterns on titanium surfaces to control cell adhesion and spreading on dental implants, thereby improving osseointegration. The DLIP structures have spatial periods of 3, 5, 10, and 17 μm. They are produced using a laser source with a pulse duration of 10 ps and cumulated energy densities between 0.1 and 78.9 J cm−2. Laser‐induced periodic surface structures (LIPSS) and submicron features are obtained on the treated samples. The DLIP treatment leads to the development of a thick titanium oxide layer, which is imaged and quantified using time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS). Several days (30–56) after the laser treatment, specimens with larger spatial periods are hydrophilic, whereas samples with spatial periods of 3 μm are hydrophobic. Seeded human osteoblasts on the laser‐structured samples show 2.5 times higher cell numbers after 7 days in vitro culture compared with osteoblasts on a grit‐blasted and etched reference sample. Finally, cell adhesion to a structured 3D dental implant is demonstrated.

Impact performance and microstructures of thick TA1 titanium alloy sheets welded by vacuum electron beam

Thick TA1 titanium alloy sheets were thoroughly bonded by vacuum electron beam welding (EBW). The results indicated that microstructures in the weld zone (WZ) consisted of coarse α columnar grains, serrated α as well as needle-shaped α′; the microstructure in the heat-affected zone near the WZ side was composed of α′ and α, while the microstructure near the base metal side consisted of α″ and α. The positional relation between the notches and rolling direction had an important role in the impact performance. The EBW joint exhibited higher absorbed impact energy at the weld seam after local heat treatment. Furthermore, lots of dimples were produced on the impact fracture surfaces, exhibiting ductile fractures.

Characterization and mechanical properties of thick TC4 titanium alloy sheets welded joint by vacuum EBW

The thick TC4 titanium alloy sheets were welded by vacuum electron beam welding (EBW). The results indicated that the elongation of TC4 joint was significantly less than that of BM, indicating that ductility and plasticity of this joint was poor due to the formations of large quantity of the martensites in weld zone (WZ). Local heat treatment (LHT) led portion of α to be broken up, portion of α′ became primitive β+α during a LHT process, resulting in staggered fine/short piece-shape phases; also α can be observed in the crystals’ boundaries of β; the tensile strength and elongation of LHT samples were significantly higher compared with those of same samples free of LHT. To have quantitative understanding of EBW of thick titanium alloy sheets and LHT effects, this paper has provided the technological and related theoretical basis to join TC4 sheets also further improve the mechanical performance of this joint.

Study on Damage Mechanism of Ultrasonic Radiation Rod in Aluminum Alloy Casting

Abstract Ultrasound has been applied to aluminum alloy casting to improve the properties of the alloy. However, the damage caused by the ultrasonic radiation rod seriously affects the continuous and steady propagation of ultrasonic waves in the molten aluminum. In this work, a 34-mm long and 20-mm thick titanium alloy plate was cut from the intermediate position of a radiation rod that had been severely eroded. Thereafter, 24 specimens were cut from the titanium alloy plate, and their damage interface was observed by scanning electron microscopy. The results show that the damage of the radiation rod is mainly caused by the ultrasonic cavitation effect and chemical reaction, which provides theoretical guidance for the protection of the radiation rod.

Evaluation of Photocatalytic and Protein Adsorption Properties of Anodized Titanium Plate Immersed in Simulated Body Fluid.

Titanium-based materials are widely used for implant treatments such as artificial dental roots. Surface treatment has the potential to improve not only the biocompatibility but also the chemical and mechanical durability of the surface without changing the mechanical properties of the metal. A relatively thick titanium oxide film can be formed by the anodic oxidation method. Phosphoric acid or sulfuric acid electrolytic solution has previously been used for anodic oxidation. Such anodized films have excellent film hardness, abrasion resistance, and adhesion. In this study, titanium plate was anodized using an aqueous solution of sulfuric acid in which titanium oxide powder was suspended. A 2800-nm-thick titanium oxide film was formed, which was thicker than that obtained using phosphoric acid electrolyte. The titanium plate was immersed in simulated body fluid for 1 day to evaluate the photocatalytic activity and protein adsorption ability, and a homogeneous crack-free hydroxyapatite layer was formed. This titanium plate showed high methylene blue bleaching capacity. The adsorption ability of the acidic protein of the anodized titanium plate subjected to the above treatment was high. This suggests that this titanium plate has antimicrobial properties and protein adsorption ability. Thus, we report that a titanium plate, anodized with a sulfuric acid aqueous electrolyte solution containing suspended TiO2 powder and immersed in simulated body fluid, might behave as an antibacterial and highly biocompatible implant material.

Addressing the dose perturbation of metallic implant in spinal Stereotactic Body Radiotherapy (SBRT)

This study compares methods of addressing the dose perturbation occurred in planning and delivery stage of spinal adjuvant Stereotactic Body Radiotherapy (SBRT) caused by the presence of titanium implants. Dose prediction by TPS was conducted while the CT number of titanium was (a) default, calculated by AAA algorithm (“No Overridden”); (b) relative electron density, mass density matched, calculated by AAA algorithm (“AAA”); (c) relative electron density, mass density matched, calculated by AXB algorithm (“AXB”). In (i) phantom study, dose predictions were compared with measurement conducted with 2 mm, 6 mm and 10 mm thickness of titanium alloy Grade 5 (Ti6Al4V) using field sizes of 1 × 1 cm2, 2 × 2 cm2, and 4 × 4 cm2. In (ii) planning study, retrospective dose predictions on patient plans were carried out to evaluate the impact on clinical outcome. The mean discrepancies (%) between measurement and “No Overridden”, “AAA”, “AXB” at tissue - titanium interface (titanium - tissue interface) were respectively -16.86 (10.93), -14.05 (11.24), 0.71 (1.54) for 2 mm and 6 mm thickness of titanium; and -18.42 (11.20), -18.29 (11.04), -10.14 (0.01) for 10 mm thickness of titanium, respectively. The patient study results by “AXB” yielded a significant deficit in tumour volume coverage at prescribed dose compared to “AAA” and “No Overridden” by 5.23 % and 9.06 %, respectively. “No Overridden” and “AAA” can potentially generate acceptable prediction in specific scenarios where the depth of target remains approximately unchanged while the gantry rotates. The AXB algorithm is recommended to be used in routine practice involving titanium implants.

Determination of nanoscale titanium oxide thin film phase composition using X-ray photoelectron spectroscopy valence band analysis

The phase compositions of nanoscale thick titania films on the titanium were determined using X-ray photoelectron spectroscopy valence band analysis for the first time, by deconvoluting the two-peak structure of valence band into five peaks and analyzing the relative peak area. The titania films of thickness varying from about 2 nm to 8 μm were obtained by the air oxidation of commercially pure titanium at different temperatures. The titania films formed on titanium for oxidizing temperatures up to 200 °C were amorphous, with thickness < 10 nm. The sub-stoichiometric oxides present at the TiO2-Ti interface were composed of Ti3+, Ti2+ and Ti1+ states when the film of thickness was <10 nm. At 300 °C, when the titania film thickness was <20 nm, it was fully converted to rutile phase and remained stable up to 1000 °C. A broadening of full-width half-maxima of the core level peaks for the titania layers was attributed to the presence of surface hydroxyl group and stress gradient within the oxide layer. The absence of metastable anatase phase in the titania layers at lower temperatures was attributed to the presence of high stresses within the oxide layers owing to their nanoscale thickness.

The porosity formation mechanism in the laser welded joint of TA15 titanium alloy

The laser welding of 5 mm thick TA15 titanium alloy was realized by fiber laser of IPG YLS-6000. The microstructure and porosity formation mechanism of the welded joints were investigated under different welding conditions. The microstructure and porosity of welded joints were observed using optical microscope and energy dispersive spectrometer (EDS), respectively. Moreover, the influencing mechanisms of porosity formation and evolution induced by metallurgical and instability of keyhole were also discussed. The experimental results indicated that the outline of metallurgical porosity is regular, which is mainly caused by the absorption of water from the outside environment into the molten pool and the evaporation of Al element. Fast welding speed contributes to the keyhole fluctuating sharply or even collapsing, which causes the shielding gas to enter the molten pool and further form bubbles. The fundamental reason for the formation of porosity is that the laser welding speed is so fast that the molten pool cooling speed is high, which makes it difficult for dissolved gas to escape sufficiently and finally form porosities. It lays foundation for understanding the formation mechanism of porosity and optimizing the process for laser welding of TA15 titanium alloy.

Vanadium disulfide flakes with nanolayered titanium disulfide coating as cathode materials in lithium-ion batteries

Unlike the vast majority of transition metal dichalcogenides which are semiconductors, vanadium disulfide is metallic and conductive. This makes it particularly promising as an electrode material in lithium-ion batteries. However, vanadium disulfide exhibits poor stability due to large Peierls distortion during cycling. Here we report that vanadium disulfide flakes can be rendered stable in the electrochemical environment of a lithium-ion battery by conformally coating them with a ~2.5 nm thick titanium disulfide layer. Density functional theory calculations indicate that the titanium disulfide coating is far less susceptible to Peierls distortion during the lithiation-delithiation process, enabling it to stabilize the underlying vanadium disulfide material. The titanium disulfide coated vanadium disulfide cathode exhibits an operating voltage of ~2 V, high specific capacity (~180 mAh g−1 @200 mA g−1 current density) and rate capability (~70 mAh g−1 @1000 mA g−1), while achieving capacity retention close to 100% after 400 charge−discharge steps.

Monte-Carlo simulation of ion distributions in a gas cell for multinucleon transfer reaction products at LENSHIAF spectrometer

The multinucleon transfer (MNT) reaction is one promising way to produce neutron-rich heavy nuclei and even super heavy nuclei and attracts more and more attentions theoretically and experimentally. A low energy nuclear structure spectrometer called LENSHIAF specific to the MNT reactions will be designed and constructed in the ongoing big project HIAF in China. In the LENSHIAF spectrometer, the most challenge part is how to collect and stop efficiently the high-energy MNT products into the gas cell. By using Monte-Carlo method, the geometry of the gas cell, the thickness of the titanium window/degrader, and the optimal gas pressure filled in the gas cell have been calculated and estimated. For neutron-rich nuclei around N = 126 from 136Xe + 198Pt reaction, with a titanium window/degrader with a thickness of 2.5–3.5 μm, a cylindrical helium gas cell with a length of 0.6 m and a diameter of 1.2 m can satisfy the requirements to stop the target-like fragments. For heavier and super heavy nuclei from 238U + 238U reaction, with a 5–8 μm thick titanium window/degrader, the cylindrical gas cell has to be as big as a length of at least 1.6 m and a diameter of 1.6 m.

The fabrication of nanostructured titania polymorphs layer with high crystallinity and its apatite-forming ability

High crystallinity anatase/rutile layers are prepared on the surface of commercially pure titanium (cpTi) by hydrothermal method at 160 °C for 3 h. The surface morphology of titania layers is changed by adjusting the pH value and Ti4+concentration of treating solution (TS). Obtained nanorods on all TS samples are composed of pure rutile and the anatase co-deposited with rutile is found in the dense bottom layer. The possible co-deposition mechanism of polymorphs layers is given in this study. In this study, the rutile nanorods array with high energy (101) facet exposed is found on the TS3 sample. In vitro apatite forming ability of the TS samples are confirmed by soaking them in Kokubo's simulated body fluid (SBF, pH 7.4, 36.5 °C) for 1 and 3 days. Results show that apatite particles could be obtained on all TS samples within 1 d. After 3 days' immersion in SBF, TS3 sample shows strongest apatite X-ray diffraction. These results indicate that the ability in inducing apatite on cpTi with TS3 treatment is excellent. Such excellent apatite-forming ability is ascribed to the existence of thick titania layer with high energy (101) facet exposed on the TS3 sample.

Evaluation on Residual Stresses in Thick Titanium Welded Alloys

In this work, both Finite element simulated method and contour method experimental measurement are used to obtain residual stresses of different Titanium welded alloys, the results show that the maximum of the residual stress is mainly related to the internal restraint degree which formed inside of the thickness, the distribution of the residual stress depends primarily on the shape of weld shape. The heating stage plays a major role in relaxing the residual stress in this research. 95% of the residual stress is relieved in the temperature rising period, and about 75% of it is relieved in the temperature rising period when the temperature is above 500°C.