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Catalytic metal hydride hydrogen atom transfer (MHAT) reactions have proven to be a powerful method for alkene functionalization. This work reports the discovery of Co‐porphines as highly efficient MHAT catalysts with a loading of only 0.01 mol % for unprecedented chemoselective allene functionalization under photoirradiation. Moreover, the newly developed bimetallic strategy by the combination of photo Co‐MHAT and Ti catalysis enabled the successful carbonyl allylation with a wide range of amino, oxy, thio, aryl, and alkyl‐allenes providing expedient access to valuable β‐functionalized homoallylic alcohols in over 100 examples with exceptional regio‐ and diastereoselectivity. Mechanism studies and DFT calculations supported that selectively transferring hydrogen atoms from cobalt hydride to allenes and generating allyl radicals is the key step in the catalytic cycle. [ABSTRACT FROM AUTHOR]

The formation of the Ti substituted Mg 2 Ni alloys, a promising hydrogen storage material for various applications is studied in detail. Mg 1.95 Ti 0.05 Ni alloy and ribbons are successfully prepared by vacuum arc melting and melt spinning methods. The phases, microstructures, and thermal behavior of the alloys and ribbons are characterized by XRD, SEM, TEM, DTA/TG. Sievert-type apparatus is used to study hydrogen sorption properties. Apart from the dominant Mg 2 Ni phase, the formation of MgNi 2 , Mg, and Ni 3 Ti phases is seen in both Mg 1·95 Ti 0·05 Ni alloy and ribbons. During the initial three cycles, Mg 1·95 Ti 0·05 Ni ribbons showed 2 wt % hydrogen storage capacity. To explain the atomic-scale influence of Ti dopant in the studied alloys and hydrides, FP(L)APW + lo method based on Density Functional Theory (DFT) is applied to Mg 2-x Ti x Ni (x = 0.25 and 0.5) alloys and Mg 2-x Ti x NiH 4 (x = 0.25 and 0.5) hydrides. An increase in the Ti dopant on the Mg site leads to the hydrides destabilization. Bader's charge density topology analysis provides insight into the charge transfer and bonding between the constituent atoms. • Partial substitution of a low amount of Ti was carried out in Mg 2 Ni intermetallic alloy. • The melting temperatures of the intermetallic Mg 2 Ni phases in Mg 1·95 Ti 0·05 Ni alloy and ribbons are about 725 °C. • Hydrogen storage capacity of Mg 1·95 Ti 0·05 Ni ribbons reaches 2 wt% at 350 °C. • Ti reduces the stability of the hydride by weakening the binding energy. [ABSTRACT FROM AUTHOR]

We synthesized an amorphous Ti-based hydroperoxo complex (ATPC) using a facile method involvingonly titanium hydride (TiH2) and H2O2 under mild conditions. We chose TiH2 as the precursor because it has more reactive sites than metal oxides such as TiO2. Qualitative and quantitative optical measurements showed that our synthesized ATPC photocatalysts contained many hydroperoxo groups and various oxidation states of Ti (Ti2+, Ti3+, and Ti4+). Thus, the synthesized ATPC exhibits excellent photocatalytic properties with very fast rates of organic decolorization compared to other conventional visiblelight catalysts. The presence of many hydroperoxo complexes increases the formation of active radicals, which can degrade VOCs such as acetaldehyde in a gas phase. To test the application of the synthesized ATPC, we fabricated a filter system in an air purifier using ATPC coating layers and successfully removed the VOCs. We also proposed a possible photocatalytic oxidation mechanism with ATPC based on this study. It is important to conduct application tests as well as commercialization in photocatalytic experiments. [ABSTRACT FROM AUTHOR]

The choice of foaming agent and its mass fraction significantly affect the size and number of metal foam cells. The powder metallurgy process was used to produce aluminium foams with the addition of various foaming agents: titanium hydride (TiH2) and calcium carbonate (CaCO3). TiH2 was added in an amount of 0.4 wt.%, while the quantity of CaCO3 varied between 3 and 5 wt.%. The produced foams, with approximately the same degree of porosity, were scanned using a non-destructive computed tomography method. The number, size, equivalent diameter, sphericity, and compactness of cells were analysed on the obtained three-dimensional models. The results showed that foams foamed with TiH2 have much larger cells compared to CaCO3 agent. By considering the influence of CaCO3 fraction on the morphology of aluminium foam, it follows that a smaller quantity of CaCO3 (3 wt.%) provides a macrostructure with smaller cells. Samples with five wt.% CaCO3 contain slightly larger cells but are still much smaller than foams with TiH2 foaming agent at the same degree of porosity. The sphericity and compactness indicate that TiH2 foaming agent forms cells of a more regular shape compared to CaCO3 agent. [ABSTRACT FROM AUTHOR]

The abundant metal Ti is a high-quality metal with lightweight, high strength, and corrosion resistance. However, due to its harsh preparation conditions, the price remains high, so titanium metal's simple and effective products have become a challenge for the world's scientific research community. In this paper, by calculating the oxygen potential of Ti–O, Ti–H, and Ti–H–O solid solutions, the oxygen potential of Ti–H–O was obtained when the oxygen content was 0.03 and 0.009. As H2 enters the Ti–O lattice, the oxygen potential of the Ti–H–O system increases with the increase of H content. Thermodynamic calculations showed that introducing hydrogen effectively destroyed the stability of Ti–O solid solutions. At the same time, this paper uses a magnesiothermic as a reducing agent. To verify the feasibility of the above thermodynamics, reduce the spent V2O5–WO3/TiO2 catalyst (Ti > 80 wt%) of titanium-rich materials in a hydrogen atmosphere. Finally, the spent V2O5–WO3/TiO2 catalyst was reduced at 750 °C for 8–24 h to obtain TiH2 powder with an oxygen content of 0.9 wt%.

Interfacial solar driven water evaporation (ISDWE) and photocatalytic pollutant degradation (PPD) have been considered as efficient and green technologies for tackling the water crisis. Here, through hydrothermal treatment of TiH 1.924 /Ti powders, we designed a hybrid material composed of partially oxidized TiH 1.924 and TiO 2 nanosheets with outstanding ISDWE and PPD performances. Titanium suboxides can be formed inside the compound of partially oxidized TiH 1·924 /TiO 2 nanosheet, and induce efficient solar-thermal transformation. Meanwhile, TiO 2 nanosheet is conducive to reducing the water vaporization enthalpy, ensuring adequate water supply, and enlarging the surface area for evaporation. Due to the synergies between partially oxidized TiH 1.924 and TiO 2 nanosheet, the water evaporation rate achieved 1.70 kg m−2•h−1 under solar radiation of 1.0 kW m−2, which is higher than most reported titanium compounds. The investigation on the PPD performance showed that the photothermal effect and band alignment collaboratively improved the photodegradation of rhodamine B by partially oxidized TiH 1·924 /TiO 2 nanosheets. The excellent PPD property can promote the long-term ISDWE application of partially oxidized TiH 1·924 /TiO 2 nanosheets by avoiding the dye accumulation. This study may provide valuable information for developing advanced composites, ISDWE and PPD technologies. [ABSTRACT FROM AUTHOR]

The effect of a dispersed powder filler obtained by thermal synthesis from the reaction mixture of 65 wt.% titanium hydride, 30 wt.% ferrosilicon manganese, and 5 wt.% boron carbide, on the basic physicomechanical properties of an ED-20 epoxy diane oligomer-base composite was studied. The filler content in the composite varied in the range of 5-80 wt.%. Its optimum content providing an essential improvement of the mechanical composite properties [strength and impact toughness (by 1.7-2.3 times compared to the parent matrix)] was established to be 10 wt.%. A further increase in the filler content to 20–60 wt.% results in a slight decrease of fracture stresses whose level, however, still exceeds the strength level of the parent matrix phase, while at 80 wt.%, the fracture stresses decrease almost to the strength level of filler-free epoxy resin. The physical substantiation for the extremum on the relation between the basic mechanical composite properties and filler content built on the hypothesis of the independent effect of mechanical and structural factors on the composite properties is advanced. In contrast to the cohesive composite properties, the addition of 5–20 wt.% of dispersed filler to the epoxy matrix does not lead to fundamental changes in the adhesion strength level (22.0-26.4 MPa), while with an increase to 40–60 wt.% results in a noticeable decrease in the adhesion strength, and at 80 wt.%, the adhesion strength drops catastrophically to 10.7 MPa. The residual stresses in the filler-containing coating are reduced by 2.5-5 times compared to the filler-free parent epoxy matrix. [ABSTRACT FROM AUTHOR]

Porous materials are very efficient in absorbing mechanical energy, for instance, in combined armor, in order to improve the anti-ballistic protection characteristics. In the present study, porous titanium-based structures were manufactured via three different powder metallurgy methods using titanium hydride (TiH2) powder, which provided activated sintering, owing to dehydrogenation. The emission of hydrogen and shrinkage of powder particles on dehydrogenation also added an additional potential to control the sintering process and create desirable porosities. TiH2 powder was sintered with additions of NaCl or ammonium carbide as pore holding removable agents, while highly porous Ti-Al structures were formed via liquid phase reactive sintering of TiH2 and Al powders. The microstructures and porosities of sintered dehydrogenated titanium and Ti-Al structures were comparatively studied. Mechanical characteristics were evaluated using compression testing with strain rates varying from quasi-static to high levels. The resonant frequency method was also employed to determine damping parameters and elastic modulus of these materials. All testing methods were aimed at characterizing the energy-absorbing ability of the obtained porous structures. The desired strength, plasticity and energy-absorbing characteristics of porous titanium-based structures were assessed, and the possibilities of their application were also discussed. Based on the obtained results, it was found that porous titanium materials produced with the use of ammonium carbonate showed promising energy absorption properties. [ABSTRACT FROM AUTHOR]

One concern regarding the used nuclear fuel containers proposed for use in a Canadian deep geological repository (DGR) is the possibility that a small amount of hydrogen might be absorbed into their copper coating, potentially altering its mechanical properties. Reported herein is a study of hydrogen absorption into 50 nm of copper, coated on 4 nm of Ti using in situ neutron reflectometry (NR) and electrochemical impedance spectroscopy (EIS). NR results show that hydrogen is absorbed when the copper is cathodically polarized below the threshold for the hydrogen evolution reaction (HER), but that the hydrogen concentrates in the underlying titanium layer rather than concentrating in the copper coating. The hydrogen concentration in titanium rapidly rose when the HER was initiated and was observed to reach a steady state at TiH1.5. Over the course of 55h of cathodic polarization, the concentration of hydrogen in the copper remained below the NR detection limit (2 at %). The portion of hydrogen atoms produced that diffused through the copper layer was initially 3.2%, suggesting a possible upper limit for hydrogen uptake by the copper coating of the UFC, although definitive conclusions can only be drawn from studies on 3 mm copper-coated steel samples. [ABSTRACT FROM AUTHOR]

Closed-pore cellular aluminum was experimentally made using recycled commercial post-consumer aluminum containers as an extremely fine powder (below 32 µm) and calcium carbonate (CaCO3) as a foaming agent, replacing the much more expensive titanium hydride (TiH2) frequently used. The aluminum powder was processed by the own original method of microwave melting and atomizing by contact with nitrogen jets. The mixture foaming was performed by irradiation heating in microwave field at 750 °C. The main characteristics of aluminum foam specimens (apparent density in the range of 0.88-1.10 g·cm-3, heat conductivity between 3.30-5.65 W·m-1·K-1, compression strength within the limits 3.9-7.4 MPa, and homogeneous microstructure with cell size below 0.45 mm) were almost similar in terms of quality with products made with TiH2. [ABSTRACT FROM AUTHOR]

The development of titanium (Ti) powder production process is important because Ti powder metallurgy (PM) is a promising method that can result in large cost savings by reducing material loss and the number of steps in the conventional manufacturing process of Ti metal and its alloys. This study investigated the process of producing Ti hydride powder directly from titanium tetrachloride (TiCl4) using magnesium (Mg) metal and hydrogen gas (H2). The experiments were conducted at 10731173K when the TiCl4 feeding rate was in the range of 19.1657.42 g·min-1 with the use of cooling gas as Ar or H2 gas. A mixture of Ti and Ti hydride (TiH1.5) was obtained in an iron (Fe) crucible by the dehydrogenation of Ti hydride as the TiCl4 reduction proceeded. The concentration of oxygen (O) decreased with a decrease in the specific surface area and/or an increase in the proportion of TiH1.5 in the powder. As a result, the concentration of O of the mixture of Ti and TiH1.5 decreased to 0.116 mass% under a certain condition. [ABSTRACT FROM AUTHOR]

The negative infl uence of oxygen, nitrogen, and carbon admixtures in titanium hydride production is shown. The procedures were developed for determination in titanium hydride of the content of carbon admixtures in ceramic crucibles, and of oxygen and nitrogen in graphite crucibles by stepwise heating. Removal of the gas phase and part of the adsorbed layer of admixtures from the titanium hydride allows reducing the amount of oxygen and nitrogen admixtures in it by approximately 3 times. A procedure was developed for determination of hydrogen content in titanium hydride by burning this compound in a fl ow of gaseous oxygen with н2 о formation. Recommendations are provided as regards the instruments to be used for analysis of titanium hydride for hydrogen content. The problem of formation of titanium hydride with superstoichiometric hydrogen content is considered. The papers published on this subject do not provide a convincing proof of the existence of such hydrides. [ABSTRACT FROM AUTHOR]

Quantum description of the isothermal and adiabatic magnetocaloric effect (MCE), thermomagnetic properties, and energy spectra of three diatomic molecules, namely: lithium hydride (LiH), titanium hydride (TiH), and scandium hydride (ScH), was examined with Deng-Fan-Screened Coulomb Potential using the Greene-Aldrich approximation to the centrifugal term. The numerical solutions of the proposed potential with and without the magnetic and AB flux fields obtained reveal that the combined impacts of the magnetic and AB flux fields completely remove the degeneracy of the energy spectra and control the behaviour of the MCE by acting as a regulating factor to cool or heat the MCE. Also, the proposed potential reduces to three exceptional cases, and the thermomagnetic plots obtained for the analysed dimer molecules agreed perfectly with previous work. This research has the potential to be applied in molecular physics and MCE studies for a variety of molecules. [ABSTRACT FROM AUTHOR]

A TiTaNbZrHf refractory high-entropy alloy (RHEA) was synthesized through a cold isostatic pressing and a pressure-less sintering process in a hydrogen atmosphere using a powder mixture of metal hydride prepared either by mechanical alloying (MA) or by rotating mixing. This study investigates how differences in powder particle sizes impact the RHEA's microstructure and mechanical properties. HCP (a = b = 3.198 Å, c = 5.061 Å) and BCC2 (a = b = c = 3.40 Å) phases were observed in the microstructure of coarse powder TiTaNbZrHf RHEAs at 1400 °C. In contrast, fine powder RHEAs were found to possess two-phase structures of HCP and BCC1 (a = b = c = 3.36 Å) with a higher hardness of 431 HV, compression strength of 1620 MPa, and a plasticity of >20%. [ABSTRACT FROM AUTHOR]

The influence of manufacturing parameters (particle size fractions of powder, compaction pressure, sintering temperature) of titanium hydride TiH2 on the microstructural evolution and corrosion resistance of porous titanium in inorganic acids (20 wt.% HCl and 40 wt.% H2SO4 solutions) was investigated. It was shown that the porosity was fixed in the powder metallurgy titanium regardless of the manufacturing parameters. By decreasing particle size fractions of powder (from 100–200 μm to 0–100 μm) and increasing compaction pressure (from 150 MPa to 650 MPa) and sintering temperature (from 1050°C to 1350°C), the porosity of titanium was decreased from 5.1% to 1.1%. It was determined that a decrease of the porosity improves the anticorrosion properties of sintered titanium investigated by potentiodynamic polarization and static immersion tests. The highest corrosion resistance in the inorganic acids was obtained for porous titanium (1% porosity), which was pressed at 650 MPa and sintered in a vacuum at a temperature of 1350°C. [ABSTRACT FROM AUTHOR]

The manufacturing of in situ reinforced titanium matrix composites by the sintering of titanium hydride and ceramic powder blends is an attractive and cost‐efficient process. Herein, a novel two‐stage (double‐compaction/double‐sintering) hydrogen‐assisted powder approach is suggested to produce uniform highly dense Ti‐based composites reinforced with TiB, TiC, and dual TiC + TiB phase particles. In this approach, the hydrogenation and milling of presintered products enable the initial porous materials to transform into hydrogenated prealloyed (PA) powders of controlled sizes, and a second press‐and‐sinter process further converts the PA powders into nearly dense composite microstructures with evenly distributed fine reinforcements. The adverse effect of the raw reinforcing powder size on microstructure uniformity, porosity, and mechanical characteristics of the presintered in situ composites becomes negligible in final sintering stage. The reduction of the porosity and enhancement of the hardness indicate that the hydrogen‐assisted double‐compaction and double‐sintering blended elemental powder metallurgy (BEPM) + PA approach enables the low‐cost fabrication of Ti‐based composites with suitable mechanical characteristics. [ABSTRACT FROM AUTHOR]

The structure changes, microstructure evolution, and mechanical properties during Powder Metallurgy (PM) through High Vacuum Sintering of a Ti-TiH2 matrix reinforced with Titanium Diboride (TiB2) particles were investigated. Composites were fabricated at 850, 1100, and 1300 °C. The strategy for the fabrication process was to use the PM route employing titanium hydride (TiH2) to reduce the consumption of Commercially Pure Titanium (CP-Ti). The structure of the composites was analyzed using X-Ray Diffraction (XRD), while Optical Microscopy (OM), and Field-Emission Scanning Electron Microscopy (FE-SEM) analysis were used to study the microstructure. Vickers microhardness and nanoindentation were performed to evaluate the elastoplastic and mechanical properties. According to the results, the unreinforced Ti-TiH2 sample presented higher sinter-ability, attaining relative density values of 93% with the higher sintering temperature. Composite samples showed TiB and TiB2 phases without the presence of any TiH2 residual phase. The highest mechanical properties were measured for reinforced samples with 30 vol.% of TiB2, sintered at 1300 °C, showing values of 509.29 HV and 4.94 GPa for microindentation Vickers and nanoindentation essays, respectively, which resulted in 8.5% higher than the values for the unreinforced sample. In addition, their H/Er and H3/Er2 ratios are higher than those of CP-Ti suggesting a better wear resistance of the Ti-TiH2 matrix-reinforced samples, combined with its mechanical properties makes it more suitable than CP-Ti for its potential in biomedical applications. [ABSTRACT FROM AUTHOR]

The powder metallurgy (PM) route for the production of closed-cell metallic foams has recently received a significant amount of attention. One of the major issues is the non-uniform and non-spherical nature of the cells produced, which can negatively affect the mechanical behavior. The current paper uses the PM route to process metallic foams for the first time using novel Al-TiH2 foamable precursor “particles” (FPPs). The effect of FPP content (0–10 wt.%) on the developed foam structure of aluminum and its mechanical properties is investigated. An increase in FPP content results in a decline in product density by forming uniform and near-spherical cells. The main advantage of the FPPs is the localization of the blowing agent TiH2 particle content within Al-TiH2 composite particles (i.e., giving rise to a higher local TiH2 content), which has led to the production of pores with relatively high circularities even at very low overall TiH2 contents. The foams produced displayed energy absorption capacities of 10–25 MJ/m3 at 50% strain, and maximum energy absorption efficiencies ranging from 0.6–0.7 (for 40–60% closed cell content)

C27H27Cl2N3O6Ti, monoclinic, P21/c (no. 14), a = 11.609(4) Å, b = 21.476(7) Å, c = 13.504(4) Å, β = 109.881(9)°, V = 3166.2(18) Å3, Z = 4, Rgt(F) = 0.0623, wRref(F2) = 0.1945, T = 100(1) K. [ABSTRACT FROM AUTHOR]

Fabrication of high-performance titanium (Ti) alloys containing high-melting-point elements is challenging via blended elemental powder metallurgy (BEPM), because of the inevitable high porosity induced during pressing and sintering processes. Herein, we propose a novel master-alloy pre-hydrogenation (MAPH) method to fabricate sintered TC16 (Ti-3Al-5Mo-4.5 V) alloy, which possess a nearly full-density (99.2%) and good mechanical properties, i.e., an UTS of ∼ 1004.6 MPa, a YS of ∼934.2 MPa and an EL of ∼15.8%. The pre-hydrogenated 7.5Ti-3Al-5Mo-4.5V-Hx (7.5TiMA-Hx) powder particles show a morphology of sharp corners. Therefore, the 7.5TiMA-Hx and TiH2 particles can get interlocked compactly during compaction and shrink simultaneously during the dehydrogenation process, which minimizes the difference in volume mismatch and ensures the overall uniformity after sintering. Besides, the interlocking compact structure makes the element diffusion easier between the 7.5TiMA-Hx and TiH2 matrix particles, which promotes the healing of porosity. The low porosity can reduce the tendency for propagation of cracks along the grain boundaries of the α layer, leading to a good balance between the strength and ductility of the sintered TC16-7.5TiMA-Hx alloy.

Mechanism of Hydrogen-induced defects and cracking in Ti and Ti–Mo alloy was systematically analyzed from the perspective of microstructure. Results show that more hydrogen atoms can be dissolved in Ti–Mo alloy due to the existence of β phase, and the precipitation amount of hydride is reduced under the same hydrogen charging conditions. The analysis of positron annihilation results show that the solid solution of Mo element reduces the hydrogen induced defect concentration in the alloy and inhibit the combination of hydrogen and defects. At the same time, Mo atom can affect the electronic structure of Titanium hydrides, and then reduce the bonding between titanium atoms and hydrogen atoms, thereby reducing the formation of brittle titanium hydride. The reduction of hydride and hydrogen induced defect concentration significantly decrease the hardening rate of Ti–Mo alloy, thereby effectively reducing the hydrogen embrittlement sensitivity of titanium and inhibiting its hydrogen absorption cracking tendency. • The formation of β phase in Ti–Mo alloy improves the solubility of hydrogen, thereby reducing the precipitation of hydride. • The solid solution of Mo can affect the electronic structure of titanium hydride and weaken the bonding between Ti–H. • The solid solution of Mo can reduce the concentration of hydrogen-induced defects in Ti–Mo alloy. • Reducing the concentration of hydride and hydrogen induced defect can inhibit hydrogen absorption cracking tendency. [ABSTRACT FROM AUTHOR]

The effect of Ti content in various concentrations as an alloying element with Al on both microhardness and crystallization structure of aluminum–titanium alloys was studied, utilizing x-ray diffraction (XRD) and a scanning electron microscope (SEM). To study the electrochemical and corrosion performance of Al and its investigated alloys in 0.5 M solutions of HCl and H3PO4, two different techniques were used: extrapolation of Tafel plot and electrochemical impedance spectroscopy (EIS). Tafel plots and EIS revealed a similar trend. Generally, the rate of corrosion of the alloys was higher than that of Al. This investigation exhibited that the corrosion of Al alloying with Ti increased with an increase in both Ti content and temperature, which is due to reducing the growth of oxide film on the surface. Changes in the standard values of both entropy (ΔS) and enthalpy (ΔH), in addition to apparent activation energy (Ea) of corrosion processes of Al and its alloys in HCl and H3PO4, were evaluated. The evaluated data indicated negative values of ΔS, while the values of ΔH were positive. Besides, the decrease in ΔH value with the increase of Ti content in the alloy revealed that the dissolution of the studied alloys was fast. The positive values of ΔH were accompanied by an endothermic process. On the other hand, the activation energy (Ea) was decreased as a result of Al alloying with Ti in the two mentioned acids. Those results were supported by the corrosion current density (icorr.) and impedance parameters. By comparing the data obtained for both HCl and H3PO4 in all investigated electrodes, the corrosion current density (icorr.) in H3PO4 was lower than that in HCl. Such behavior can be ascribed to the aggressive attack of Cl¯ ions on the surfaces of the investigated electrodes, leading to pits formation. [ABSTRACT FROM AUTHOR]

The study belongs to the field of hydrogen materials science. A neutron diffraction study of titanium carbohydride TiC 0.50 H y was carried out in the range of hydrogen concentration у = 0.50 ÷ 0.60. It is shown that high-temperature titanium carbohydride TiC 0·50 H 0.50 of equiatomic composition has a face-centered cubic lattice (sp. gr. Fm 3 ¯ m), where hydrogen atoms are located in tetrahedral interstices. It has been established that in this alloy in vacuum, the phenomenon of hydrogen thermal emission is observed - complete removal of hydrogen with preservation of the FCC lattice of the TiС 0.50 interstitial alloy. For the first time in the Ti–C–H system, a first-order concentration phase transition FCC (sp. gr. Fm 3 ¯ m) → HCP (sp. gr. Pm 3 ¯ 1) in TiC 0.50 H y carbohydride at a hydrogen concentration y > 0.50 was discovered without changing the octahedral environment of carbon atoms and tetrahedral the surroundings of hydrogen atoms by Ti atoms. The HCP phase in vacuum is heat-resistant at temperatures T < 600 K. The unit cell volume of the hcp phase is two times smaller than the unit cell volume of the FCC phases TiC 0.50 H y and TiH 2 of equiatomic composition. The results of studying the fcc phase of the equiatomic composition of TiC 0·50 H 0.50 can be used to prepare a high-temperature hydrogen reservoir in hydrogen energy. The HCP phase can be used as a biological protective material in transport nuclear power plants and on nuclear submarines instead of titanium dihydride TiH 2. [ABSTRACT FROM AUTHOR]

Unsaturated titanium hydride (TiHX) powder has high formability and is a promising raw material for titanium-based powder metallurgy. In this work, TiH2, TiHX, and HDH Ti powders were characterized, the cold compaction behavior of the powders was investigated, and the densification mechanism was analyzed. The TiHX was a three-phase mixture containing an α plastic phase and δ and ε brittle phases through Rietveld refinement. The TiHX compacts had compressive strength of over 420 MPa (higher than TiH2 and similar to HDHTi) and relative density of over 80% (higher than TiH2 and HDH Ti) at 600 MPa. The Gerdemann–Jablonski and Cooper–Eaton equation were used to simulate the powder compaction curves and describe powder compaction behavior. The plastic deformation of TiHX powder is greater than TiH2, and the particle rearrangement is greater than HDH Ti during cold compaction. Such compaction behavior of TiHX causes an excellent green-strength–relative-density combination. [ABSTRACT FROM AUTHOR]

Influence of Fe3+ on the corrosion of titanium in H2SO4 solution without F− and with F− was investigated by electrochemical tests. The electrochemical test results showed that Fe3+ could significantly inhibit titanium corrosion in H2SO4 solution without F− and with F− by promoting the protective film formation on titanium. Titanium corrosion resistance (Rc) was positively related to the concentration of Fe3+ in H2SO4 without and with F−. A mechanism was proposed for Fe3+ inhibiting the corrosion of titanium in H2SO4 solution without and with F−. [ABSTRACT FROM AUTHOR]

Hydrogen metallurgy, as a green metallurgical technology, is one of the effective ways to reduce carbon emissions. The generation of titanium suboxides (Ti n O 2n-1 , 3 ≤ n ≤ 9) during the hydrogen reduction of ilmenite results in abundant hydrogen and heat loss. In this study, the ability of titanium suboxides to reduce ilmenite is systematically analyzed and confirmed. Thermodynamic calculations reveal that these titanium suboxides exist stably and reduce ilmenite when the reaction temperature exceeds 1100 K. Validation experiments indicate that Ti 3 O 5 can be used to reduce ilmenite to iron and rutile. Furthermore, by controlling the reduction time and holding operation in an inert atmosphere, the discovery of metallic iron particles generated inside unreacted ilmenite. This shows that titanium suboxides can reduce ilmenite, and also the metallization rate of iron is increased. This study has great guideline significance for the clean and green production of ilmenite. • The mechanism of hydrogen reduction of ilmenite is expounded. • Stable existence of titanium suboxides at reaction temperatures exceed 1100 K. • Titanium suboxides can reduce ilmenite is confirmed. • The metallization rate can be increased by holding operation. [ABSTRACT FROM AUTHOR]

Titanium hydride is widely considered as an important hydrogen storage material due to its high capacity, stability and low cost. The microstructure of titanium hydride, which is usually induced by the hydrogenation of titanium, strongly influences its storage performance. However, the relationship between the hydrogenation conditions and the derived microstructure of titanium hydride is still unclear, limiting the development of its structure design strategy. In this work, the microstructure of titanium hydride is correlated with its hydrogenation conditions through the thermodynamics and kinetics. By evaluating the effects of the hydrogenation temperature, pressure and cooling rate, three classes of the hydrogenation processes were clarified: kinetic-limited, continuous and stepwise. Besides, according to the SEM and FIB-STEM results, these different processes are confirmed to greatly vary the bulk microstructure. It is concluded that a fast and continuous transition induces a broken bulk morphology, while a stepwise process leads to a larger bulk grain size. In summary, this study presents a framework for designing titanium hydride structures by modifying phase transition processes through careful adjustment of hydrogenation parameters, namely, a condition-process-structure relationship. This relationship offers crucial guidance in managing the grain refinement or coarsening of hydrides within hydrogen storage components and metallurgical applications. • Effect of hydrogenation conditions on the microstructure of TiD x was studied by electron microscopy. • Marked SEM shows the surface morphology of TiD x exhibited negligible change after hydrogenation. • FIB-STEM shows that the cross-section morphology of TiD x varies significantly according to the hydrogenation conditions. • Three classes of the hydrogenation processes were clarified as kinetic-limited, continuous and stepwise. • Fast and continuous phase transition fractures bulk, while a stepwise one induces relative larger grains. [ABSTRACT FROM AUTHOR]

Directed energy deposition (DED), a metal additive manufacturing process, has attracted considerable attention in various industries. In the past few decades, several studies have been conducted to enhance the quality of DED-produced parts. Various studies on powder- and laser-based DED have focused on eliminating the residual pores in the fabricated parts, which decrease the mechanical strength. In contrast, this study aims at intentionally increasing the residual pores to produce a porous structure in metals called as foam metal, which realizes lightweight and excellent energy absorption properties. Despite being well-known for their attractive properties, Foam metals are rarely used due to the technical difficulties in their production, which requires special devices and entails considerable cost. The simplicity of the DED process makes it a promising approach to fabricate foam metals because it is easy to foam at the fabrication point by mixing a foaming agent, such as titanium hydride (TiH2), into the material powder. This study evaluates the DED foaming process in stainless steel alloys by changing the particle size of the TiH2 powder and the scanning path to obtain the optimal conditions for enhancing the pore dispersion. The experimental results show that, when the particle size of the foaming agent is small, the number of pores and their distribution increases. Additionally, the mechanical properties are also evaluated through compression experiments, and the energy absorption ratio is found to be higher when a smaller foaming agent is used.

The high-resolution photoelectron energy spectra of atomic titanium and its hydride anions were obtained on a slow-electron velocity-map imaging spectrometer equipped with a cold ion trap. The cold ion trap employed in the present measurement was found to be very helpful for reducing the interference from the titanium hydride anions. The electron affinity of Ti was determined to be 609.29(34) cm−1 or 75.54(4) meV. The accuracy was improved by a factor of 350 compared with the previous result. The fine structures of Ti− were clearly resolved: 70.0(12)(4F5/2), 165.2(15)(4F7/2), and 285.2(15) cm−1 (4F9/2) above its ground state 4F3/2. Moreover, the measured electron affinity and vibrational frequency of TiH can be reproduced well using the high level calculations. [ABSTRACT FROM AUTHOR]

Light harvesting, separation of charge carriers, and surface reactions are three fundamental steps that are essential for an efficient photocatalyst. Here we show that these steps in the TiO2 can be boosted simultaneously by disorder engineering. A solid-state reduction reaction between sodium and TiO2 forms a core-shell c-TiO2@a-TiO2-x(OH)y heterostructure, comprised of HO-Ti-[O]-Ti surface frustrated Lewis pairs (SFLPs) embedded in an amorphous shell surrounding a crystalline core, which enables a new genre of chemical reactivity. Specifically, these SFLPs heterolytically dissociate dihydrogen at room temperature to form charge-balancing protonated hydroxyl groups and hydrides at unsaturated titanium surface sites, which display high reactivity towards CO2 reduction. This crystalline-amorphous heterostructure also boosts light absorption, charge carrier separation and transfer to SFLPs, while prolonged carrier lifetimes and photothermal heat generation further enhance reactivity. The collective results of this study motivate a general approach for catalytically generating sustainable chemicals and fuels through engineered disorder in heterogeneous CO2 photocatalysts. Developing an efficient photocatalyst for CO2 reduction is appealing. Here, the authors report a core-shell c-TiO2@a-TiO2-x(OH)y heterostructure with surface frustrated Lewis pairs on amorphous shells which enables a new genre of chemical reactivity. [ABSTRACT FROM AUTHOR]

The 'POCOP' pincer ligand, [2,6-(OPR2)2C6H3], has been attached to titanium in both Ti(III) and Ti(IV) complexes for the first time. Using a lithium-halogen exchange route [2,6-(OPR2)2C6H3]Li ([RPOCOP]Li) can be synthesised. Both the iso-propyl and tert-butyl derivatives can be made, but only the latter isolated. These can be reacted with the Ti(III) and Ti(IV) synthons to make a range of [POCOP]TiClx species. In the presence of Ti(IV), THF and [RPOCOP]Li, an unprecedented ligand rearrangement occurs. (tBuPOCOP)TiCl2, 1, can be derivatised with alkylating agents to make bis-methyl, phenyl and neopentyl complexes. The last of these can activate H2 to make a rare example of a titanium chlorohydride, with the metal pincer fragment staying attached. EPR has been used to characterise the paramagnetic complexes and locate their electron spins, which is further validated with DFT calculations. This opens the door for this archetypical pincer ligand to be used with early transition metals. [ABSTRACT FROM AUTHOR]

The results of spectrometry with an ASD FieldSpec 3 FR spectroradiometer at wavelengths ranging from 350 to 2500 nm for hydrogenated amorphous and crystalline titanium and zirconium diborides are presented. The results were used to determine changes in the spectral characteristics of hydrogen in bulk and film TiB2 and ZrB2. The spectrometry was performed with the contact method using a Unit Contact Probe. The bulk test samples and spraying targets were prepared by the powder metallurgy method. X-ray diffraction identified that the samples had crystalline structure. Thin films of titanium and zirconium diborides were produced by magnetron sputtering of TiB2 and ZrB2 targets in an argon atmosphere. The structure of the films was studied using an EMP-100 electron diffractometer employing the transmission method at a residual pressure of ~7 ∙ 10–3 Pa. The electron diffraction patterns showed a strong 'halo' at the center, being indicative of amorphous structure of the films, promoting hydrogen transfer process. The samples were hydrogenated from the gas phase at a hydrogen pressure of 0.1 MPa and a temperature of 870 K. A critical analysis of published methods for the quantitative determination of hydrogen in high-temperature borides was provided. The spectrometry method is advantageous in that it is fast, precise, nondestructive, and surface-sensitive, and the entire spectrum is displayed in real time. The intensities of the Brackett Bβ and Balmer Hβ hydrogen lines for crystalline and amorphous TiB2 were compared, and the absorption of hydrogen by the crystalline sample was found to be 4.1 times higher than that by the amorphous one. In polycrystalline TiB2, lines with a halfwidth of 200–300 nm were observed at 500 and 750 nm, which was explained by the subbarrier tunneling of hydrogen atoms between neighboring interstitials, ranging, in particular, for many lattice parameters. The absorbed hydrogen amount in the amorphous film was 1.4 times higher than on the starting film. Magnetron sputtering of ceramic targets was known to lead to the introduction of impurities several tens of nanometers in size (short-range crystalline ordering) into the film, to which the hydrogen penetration process was sensitive. The presence of hydrogen atoms resulted in spectral bell-like curves, partially overlapping each other. By analogy with metal amorphous alloys, the shape of these curves could be explained by quasi-interstices. In the amorphous titanium diboride, a bell-like Balmer Hβ curve was observed, confirming short-range crystalline ordering. Correlation between the hydrogen absorption and the lattice energy and bonding energy of Me–B atoms was established. When hydrogen was absorbed by crystalline titanium and zirconium diborides, TiB2 was found to absorb higher amounts of hydrogen because of lower lattice energy and Ti–B atomic bond energy. As the spectroradiometer method is prompt and informative, we can recommended it for the identification of hydrogenated amorphous and crystalline ceramic materials. [ABSTRACT FROM AUTHOR]

The effects of different types of initial titanium powder and master alloy (MA) powder with different particle size distributions and pressing pressures on the mechanical properties of as-sintered samples were studied. Titanium hydride-based alloy could obtain better green density, sintered density, densification, element homogenization and mechanical properties. The alloy synthesized from single fine MA had better densification (low porosity) and element homogenization; therefore, it had better mechanical properties than the other alloys. Sintering performance was affected by specific surface and contact area and finer powder could obtain higher sintered density; hence, the combination of 0–38 μm titanium hydride powder and 0–26 μm single MA powder (60Al40V) obtained the highest sintered density (99.8%). Oxygen content seriously affected the mechanical properties of the as-sintered samples. The best combination of mechanical properties was obtained by selecting the appropriate powder combination and conditions. Optimal mechanical properties were obtained through the combination of 0–125 μm titanium hydride powder and 0–26 μm single MA under 600 MPa pressure. This alloy had a tensile strength of 999.9 MPa, a yield strength of 906.0 MPa, elongation of 17.83% and an area reduction of 29.4%. [ABSTRACT FROM AUTHOR]

The technique of SHS (self-propagating high-temperature synthesis) makes it possible to synthesize titanium hydride efficiently. Titanium powder synthesized through SHS hydrogenation and dehydrogenation in a vacuum furnace is experimentally studied. We examine the change in the microstructure and phase and chemical composition in hydrogenated and dehydrogenated titanium sponge. The titanium sponge is hydrogenated in a high-pressure SHS reactor at a hydrogen pressure of 3 MPa. It is established that SHS hydrogenation leads to a decrease in the content of oxygen and carbon impurities. After hydrogenation, the sponge contains a single-phase δ-titanium hydride having a tetragonal lattice. The particles have a shattered shape. It is confirmed that the titanium hydride obtained contains a higher amount of hydrogen (4.64 wt %). The hydrogenated titanium sponge is mechanically ground using a ball mill to bring the particle size within the range of 40–250 µm. Titanium hydride powder is dehydrogenated in a vacuum furnace at 850°C for 220 min. After dehydrogenation, titanium contains a single-phase α-titanium powder having a hexagonal close-packed lattice. There is no change observed in size and shape of the particles. The process studied makes it possible to obtain high-quality titanium powder having a required particle size distribution to be applied in various areas of powder metallurgy. [ABSTRACT FROM AUTHOR]

The paper presents calculated data on a comparative assessment of the radiation-protective properties of materials based on titanium hydride obtained by the method of multigroup modeling of protection against neutron and gamma radiation. Two types of compositions behind the steel reactor vessel and lead shielding are considered. It is shown that gamma radiation behind the protection of titanium hydride is formed by capture radiation arising in the initial layers of the protection. Secondary gamma radiation generated during the passage of a neutron flux through the thickness of the composite does not have a noticeable effect on the value of the functionals of gamma quanta behind the shield. The high efficiency of materials based on titanium hydride shot is shown. Behind the protection of a composite based on titanium hydride shot 1 m thick, the dose rate of fast neutrons is three orders of magnitude lower, and the dose rate of gamma rays is two orders of magnitude less than that behind serpentinite concrete. The introduction of boron atoms into the composition of the composite, which has a large neutron absorption cross section in the thermal and epithermal regions of the spectrum, reduces the effect of accumulation of thermal neutrons and the level of captured gamma radiation, but does not affect the attenuation of fast neutrons. The necessity of using titanium hydride shot on a cement binder is shown, which prevents the formation of voids in the protection structure and the passage of neutrons. [ABSTRACT FROM AUTHOR]

In the study, the two-color pyrometer technique was used to measure the transient temperature field of emulsion explosives with different contents of TiH2 powders. The experimental results showed that the introduction of TiH2 powders could significantly increase the explosion temperature and fireball duration of emulsion explosive. When emulsion explosives were ignited, the average explosion temperature of pure emulsion explosive continuously decreased while emulsion explosives added with TiH2 powders increased at first and then decreased. When the content of TiH2 powders was 6 mass%, the explosion average temperature reached its maximum value of 3095 K, increasing by 43.7% as compared with that of pure emulsion explosive. In addition, the results of air blast experiment and explosion heat test showed that the variation trends of shock wave parameters, explosion heat and theoretical explosion temperature of emulsion explosives with different contents of TiH2 powders were basically consistent with that of explosion temperature measured by the two-color pyrometer technique. In conclusion, the two-color pyrometer technique would be conducive to the formula design of emulsion explosive by understanding the explosion temperature characteristics. [ABSTRACT FROM AUTHOR]

Carbonaceous and carbon-coated electrodes are ubiquitous in electrochemical energy storage and conversion technologies due to their electrochemical stability, lightweight nature, and relatively low cost. However, traditional reliance on conductive additives and binders leads to impermanent electrical pathways. Here, a general approach is presented to fabricate robust electrodes with a progressive failure mechanism by introducing carbide-based interconnects grown via carbothermal conversion of (5 wt%) titanium hydride nanoparticles. This method concurrently enhances both electrical and mechanical properties within the electrode architecture. The resulting chemical bonding between active materials establishes a novel mechanism to maintain stable electrical pathways during cycling. Employed as Li-ion battery anodes, these electrodes exhibit improved cyclability, achieving 80% capacity retention after 800 fast-charge cycles at moderate loading (1 mAh cm - 2 ). High loading cells with areal capacity of 3 mAh cm -2 show significantly improved cycle life over the same number of cycles. This performance improvement is attributed to the absence of significant impedance growth and a thinner solid electrolyte interphase (SEI) layer formed at high current densities (4C) as demonstrated by X-ray photoelectron spectroscopy and transmission electron microscopy studies. The enhanced conductivity facilitates SEI formation, lowering ionic impedance and mitigating lithium plating, ultimately leading to the reported extended cycle life., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

Commercially pure titanium (cp-Ti) and Ti–6Al–4V alloy have emerged as excellent candidates for use as biomaterials in medical implants due to their high strength-to-weight ratio and biocompatibility. β-type Ti alloys composed of non-toxic metallic elements such as niobium (Nb) have been extensively studied in order to resolve the issue of a high elastic modulus and toxicity of certain elements, particularly in Ti–6Al–4V alloy. Titanium hydride (TiH2) has recently received a lot of attention due to its densification, oxidation levels, and material costs. Powder metallurgy combined with mechanical alloying has become an attractive route for producing near-net shape components of Ti-based alloys, mainly where porosity control and better homogeneity are required. This review aims to create a platform for investigating the feasibility of producing Ti from TiH2 via a dehydrogenation process. The dehydrogenation behaviour of TiH2 is affected by variables such as sintering condition, alloying element, and particle size. The review revealed that TiH2 decomposition occurs at various temperatures (400 °C to 800 °C), resulting in the formation of several sequences of phases. Although the dehydrogenation process was unaffected, the addition of alloying elements was found to change the starting and ending temperatures of the reactions. The use of vacuum accelerates the dehydrogenation process more than argon flow. TiH2 powder with smaller particle size, on the other hand, eliminates hydrogen faster than larger ones due to the larger surface area exposed. This review also looks at the best processing conditions for getting a high concentration of β phase in Ti–Nb alloys. β-type titanium alloys with a low elastic modulus (10–40 GPa) similar to human bone are a potential strategy for reducing premature implant failure.

Some results concerning the hydrogen effect at electrolytic saturation at a current density of j = 1500 and 3500 A/m2 for 3 h at room temperature on the temperature dependence of the yield stress σ0.1(T) and the shape memory effect (SME) under tension of the [011]-oriented Ti-50.55%Ni (at.%) alloy single crystals are presented. It was shown that hydrogen is in a solid solution and forms particles of titanium hydride TiH2 after hydrogenation at j = 1500 and 3500 A/m2, respectively. Both hydrogen in the solid solution and TiH2 particles led to a decrease in the Ms temperature of the onset of the forward martensitic transformation (MT) upon cooling and the Md temperature (Md is the temperature at which the stresses for the onset of the stress-induced MT are equal to the stresses for the onset of plastic flow of the high-temperature B2 phase), and increased the yield stress σ0.1 of the B2 phase at the Md temperature compared to hydrogen-free crystals. It was found that the SME under stress depends on the tensile stress level and current density. The maximum SME εSME = 10 ± 0.2% at σex = 200 MPa and εSME = 10.5 ± 0.2% at σex = 300 MPa was observed in the hydrogen-free crystals and after hydrogenation at j = 1500 A/m2, respectively, which exceeded the theoretical value of lattice deformation ε0 = 8.95% for the B2-B19′ MT in [011] orientation under tension. At j = 1500 A/m2, the physical reason for the excess of the SME of the theoretical ε0 value was due to the increase in the plasticity of B19′ martensite upon hydrogenation. At j = 3500 A/m2, εSME = 8.0 ± 0.2%, and it was less than ε0 = 8.95% for B2-B19′ MT in [011] orientation under tension. The decrease in SME after hydrogenation at j = 3500 A/m2 was associated with the interaction of two types of B19′-martensite: oriented under stress and non-oriented, formed near TiH2 particles. It was shown that the redistribution of hydrogen in the bulk of the crystals during long-term holding for 168 h at 263 K after hydrogenation at j = 1500 A/m2 increases the SME relative to crystals without long-term holding: 3.5 times at 50 MPa and 1.8 times at 100–150 MPa. After long-term holding, εSME = 9.5 ± 0.2% at 150 MPa, which exceeds the theoretical value ε0 = 8.95% for B2-B19′ MT in [011] orientation under tension.