Search

The electrocatalytic reduction of nitrate toward ammonia under mild conditions addresses many challenges of the Haber-Bosch reaction, providing a sustainable method for ammonia synthesis, yet it is limited by sluggish reduction kinetics and multiple competing reactions. Here, the titanium hydride electrocatalyst is synthesized by electrochemical hydrogenation reconstruction of titanium fiber paper, which achieves a large ammonia yield rate of 83.64 mg h−1 cm−2 and a high Faradaic efficiency of 99.11% with an ampere-level current density of 1.05 A cm−2 at −0.7 V versus the reversible hydrogen electrode. Electrochemical evaluation and kinetic studies indicate that the lattice hydrogen transfer from titanium hydride promotes the electrocatalytic performance of nitrate reduction reaction and the reversible equilibrium reaction between lattice hydrogen and activate hydrogen not only improves the electrocatalytic activity of nitrate reduction reaction but also demonstrates notable catalytic stability. These finding offers a universal design principle for metal hydrides as catalysts for effectively electrochemical ammonia production, highlighting their potential for sustainable ammonia synthesis. The electrocatalytic reduction of nitrate to ammonia offers a sustainable alternative to the Haber-Bosch process. Here, the authors report a lattice hydrogen transfer mechanism that enhances electrocatalytic activity by enabling reversible equilibrium reactions between lattice and active hydrogen. [ABSTRACT FROM AUTHOR]

In this research work, aluminum 6063 alloy foam was synthesized through stir casting using varying amounts of titanium hydride as a foaming agent. A comparative microstructural and wear behavior analysis of stir-cast aluminum 6063 alloy and its foam is presented. The oxide and aluminide phases present as intermetallic compounds in the stir-cast aluminum 6063 alloy foam ensure the stability of the synthesized foam. In order to optimize the effect of wear parameters on the tribological properties of stir-cast aluminum 6063 alloy foam, the L933 orthogonal array (OA) was designed and modeled statistically. The tribological properties of stir-cast aluminum 6063 alloy and its foam were evaluated by pin-on-disc tests. The optimal tribological properties of the synthesized foam are 0.29 coefficient of friction, 8.6 N frictional force, and 0.00025 mm3/N-m specific wear rate. The tribological properties of stir-cast aluminum 6063 alloy foam are superior to those of aluminum 6063 alloy and comparable to other aluminum foams described in the literature. [ABSTRACT FROM AUTHOR]

The structural, electronic, and thermodynamic properties of titanium hydride TiH 2 have been investigated using the principles of density functional theory based on the coherent potential approximation (CPA) integrated in the AkaiKKR package, with the aim of reducing the high stability and decomposition temperature to create an ideal material for hydrogen storage, thereby meeting DOE (the U.S. Department of Energy) standard conditions (formation enthalpy ΔH = −40 kJ/mol.H 2 and a decomposition temperature T des from 289 to 393 K).This study focuses particularly on the effects of titanium vacancy creation and the application of uniaxial deformation on the compound. The results show that with 12% of titanium vacancies, the formation energy increase from −122.34 kJ/mol.H 2 to −40.97 kJ/mol.H 2 and the temperature of desorption decreases from 936.045 K to 313.49 K, while −8% compressive uniaxial deformation achieve the value −41.42 kJ/mol.H 2 and 316.97 K. • Enhancing the hydrogen storage properties of titanium hydride by vacancy defects. • 12% titanium vacancies reduce the enthalpy of formation to −40.973 kJ/mol.H 2 and T des to 313.49 K. • 8% compressive uniaxial deformation decreases formation enthalpy to −41.42 kJ/mol.H 2 and T des to 316.97 K. [ABSTRACT FROM AUTHOR]

Metal hydrides enable excellent thermal energy storage due to their high energy density, extended storage capability, and cost‐effective operation. A metal hydride‐driven storage system couples two reactors that assist in thermochemical storage using cyclic operation. Metal hydride reactors, operating at both low and high temperatures, serve for the storage of hydrogen and thermal energy, respectively. The integration of efficient thermal energy storage technology is known to enhance the efficiency of solar thermal systems. In this regard, during the peak hours of solar energy, the high‐temperature supply heat can be utilized to store hydrogen gas in the low‐temperature reactor, which simultaneously facilitates energy storage in the high‐temperature reactor. Moreover, the temperature and energy released from the reactors are highly dependent on the pressure of the gas. As a result, installing a compressor between the low and high‐temperature metal hydride reactors can help generate additional outputs, such as a cooling effect. This paper conducts a thermodynamic analysis to assess the system's performance, considering parameters such as thermal storage efficiency, coefficient of performance (COP), and COPCCH (combined cooling and heating based COP). Moreover, the performance analysis was carried out for two cases, that is, high‐temperature titanium hydride (TiH2) and magnesium hydride (MgH2). The results show that MgH2 and TiH2 achieve a maximum COPCCH of 1.08 and 0.9, respectively, and system storage efficiency of 76.15% and 74.34%, respectively. In spite of having lower efficiency than MgH2, the TiH2‐based system has the ability to recover heat at a very high temperature. [ABSTRACT FROM AUTHOR]

Titanium hydride (TiH2), a promising high-energy additive, is doped into PTFE/Al to optimize the energy output structure of the reactive jet and strive for better aftereffect damage ability to the target. Six types of PTFE/Al/TiH2 reactive liners with different TiH2 content are prepared by the molding and sintering method. The energy release characteristics of PTFE/Al/TiH2 reactive jet are tested by the transient explosion energy test, and are characterized from pressure and temperature. The reaction delay time, pressure history, and temperature history of the energy release process are obtained, then the actual value of released energy and reaction efficiency of the reactive jet are calculated. The results show that the peak pressure and temperature of the PTFE/Al/TiH2 jet initially increase and then decrease with increasing TiH2 content. When the TiH2 content is 10%, the actual value of released energy and reaction efficiency increased by 24% and 6.4%, respectively, compared to the PTFE/Al jet. The reaction duration of the reactive material is significantly prolonged as the TiH2 content increased from 0% to 30%. Finally, combined with the energy release behaviors of PAT material and the dynamic deformation process of liner, the enhancement mechanism of TiH2 on energy release of the reactive jet is expounded. [ABSTRACT FROM AUTHOR]

Semi-empirical quantum models such as Density Functional Tight Binding (DFTB) are attractive methods for obtaining quantum simulation data at longer time and length scales than possible with standard approaches. However, application of these models can require lengthy effort due to the lack of a systematic approach for their development. In this work, we discuss the use of the Chebyshev Interaction Model for Efficient Simulation (ChIMES) to create rapidly parameterized DFTB models, which exhibit strong transferability due to the inclusion of many-body interactions that might otherwise be inaccurate. We apply our modeling approach to silicon polymorphs and review previous work on titanium hydride. We also review the creation of a general purpose DFTB/ChIMES model for organic molecules and compounds that approaches hybrid functional and coupled cluster accuracy with two orders of magnitude fewer parameters than similar neural network approaches. In all cases, DFTB/ChIMES yields similar accuracy to the underlying quantum method with orders of magnitude improvement in computational cost. Our developments provide a way to create computationally efficient and highly accurate simulations over varying extreme thermodynamic conditions, where physical and chemical properties can be difficult to interrogate directly, and there is historically a significant reliance on theoretical approaches for interpretation and validation of experimental results. [ABSTRACT FROM AUTHOR]

Titanium is a metal with excellent physical and chemical properties. Although it is highly abundant in the earth's crust, the difficulty of its extraction makes it expensive and restrict its application on a large scale. It has become a world problem to develop a titanium smelting method with low cost and short process. In this research, TiH1.924 powder with a low oxygen content was produced by hydrogen-assisted magnesiothermic reduction at 650 °C for 2 hours. By optimizing the thermodynamic calculation method of Ti–O–H solid solution, the thermodynamic data of Ti–O, Ti–H, and Ti–O–H with different oxygen contents have been calculated. The results showed that the hydrogen in Ti–O–H has destabilizing effect on the oxygen in Ti–O lattice. Therefore, under hydrogen atmosphere, Mg can break the thermodynamic limit of deoxidation of Ti–O solid solution, obtaining a low oxygen content reduction product. In order to further reduce the oxygen content in the product, the mechanism of secondary oxidation of the titanium hydride product was investigated, leading to the conclusion that higher hydrogen content in titanium hydride can obviously enhance its anti-oxidation property. The research can provide theoretical support for the deep reduction of TiO2 using low-cost Mg powder to obtain titanium powder with a low oxygen content. [ABSTRACT FROM AUTHOR]

MXenes, a large family of two‐dimensional carbides and/or nitrides, are among the most studied materials worldwide due to their great diversity of structures and compositions. Their unique properties find use in several applications. Typically, they are manufactured by selective wet‐chemical etching of layered MAX phase ceramics, which are produced nowadays primarily for MXene synthesis. However, the synthesis of MAX phases has not been changed since the time of their use in structural and high‐temperature applications, and it has not been optimized for MXene manufacturing. The main purpose of this study is to develop a porous Ti3AlC2 MAX phase that can be easily ground into individual grains without time‐consuming, harsh, and tedious crushing and milling steps. Moreover, we also demonstrate the synthesis of highly porous Ti3AlC2 from an inexpensive titanium sponge instead of a highly pure titanium powder and explain the mechanisms of reaction sintering and formation of porous MAX phase. MXene obtained from this MAX phase, Ti3C2Tx, shows larger flake size and higher electrical conductivity in thin films, compared to the materials produced from the costly fine titanium powder. The proposed approach may apply to the synthesis of other MAX phases as well. [ABSTRACT FROM AUTHOR]

Aluminum foams have emerged as a remarkable engineering material, exhibiting exceptional structural performance and many excellent properties. This has led to a rise in their application in various fields. The investigation and development of aluminum foam have led to the discovery of multiple applications in numerous industries, including the aerospace, automotive, petrochemical, and building materials industries. Foam made of aluminum, one of the most well-known examples of metallic foams, is a significant technological advancement in the foams industry. This article aims to comprehensively analyze the manufacturing techniques that employ blowing agents, such as alumina, titanium hydride, and sodium chloride. This article explores the unique properties and diverse applications of aluminum foams. In addition, the current status of research and development in aluminum foam is discussed. It accomplishes this by providing an overview of existing developments and identifying future opportunities in this industry. This review article is an invaluable resource for academics and industry professionals interested in aluminum foams, as it provides valuable insights into production procedures, properties, applications, and ongoing research. [ABSTRACT FROM AUTHOR]

This study explored synthesizing titanium carbide (TiC) from bitumen coke using mechanical alloying. Initially, raw bitumen coke (5.9 wt.% sulphur) from delayed coking was desulphurized to produce low sulphur coke with a sulphur content of 0.2 wt.% for comparison purposes. Both high and low sulphur coke samples were mechanically alloyed with titanium (Ti) powder in a planetary ball mill under various conditions (milling time, milling speed, and ball‐to‐material ratios [BMR]). TiC was successfully produced from both high sulphur and low sulphur coke samples. The formation of TiC was confirmed by X‐ray diffraction (XRD) analysis. The effects of the experimental parameters on the production of TiC were evaluated. The experimental results showed that the high sulphur coke and Ti were converted into TiC after 10 h milling, whereas the low sulphur coke and Ti were converted into TiC much faster (after 5 h milling) at the same milling speed and BMR. Under the same milling time and BMR, the high sulphur coke and Ti were converted into TiC at 400 rpm, whereas the low sulphur coke and Ti were converted into TiC at 300 rpm. In addition, the high sulphur coke and Ti were converted into TiC when the BMR was 60:1, and the low sulphur coke and Ti were converted into TiC when the BMR was 40:1 under the same milling time and speed. Overall, preliminary results suggest that the conversion of low sulphur coke samples is easier and requires less energy to produce TiC compared to the high sulphur coke samples. [ABSTRACT FROM AUTHOR]

The effects of the secondary processes of Hot Isostatic Pressing (HIP) at 920 °C and Heat Treatment (HT) at 1000 °C of Electron Beam-Melted (EBM) Ti–6Al–4V alloy on the microstructure and hydrogen embrittlement (HE) after electrochemical hydrogen charging (EC) were investigated. Comprehensive characterization, including microstructural analysis, X-ray diffraction (XRD), thermal desorption analysis, and mechanical testing, was conducted. After HIP, the β-phase morphology changed from discontinuous Widmanstätten to a more continuous structure, 10 times and ~1.5 times larger in length and width, respectively. Following HT, the β-phase morphology changed to a continuous "web-like" structure, ~4.5 times larger in width. Despite similar mechanical behavior in their non-hydrogenated state, the post-treated alloys exhibit increased susceptibility to HE due to enhanced hydrogen penetration into the bulk. It is shown that hydrogen content in the samples' bulk is inversely dependent on surface hydride content. It is therefore concluded that the formed hydride surface layer is crucial for inhibiting further hydrogen penetration and adsorption into the bulk and thus for reducing HE susceptibility. The lack of a hydride surface layer in the samples subject to HIP and HT highlights the importance of choosing secondary treatment process parameters that will not increase the continuous β-phase morphology of EBM Ti–6Al–4V alloys in applications that involve electrochemical hydrogen environments. [ABSTRACT FROM AUTHOR]

Titanium (Ti) is an attractive material, abundant in nature and possessing superior mechanical and chemical properties. However, its widespread use is significantly hampered by the strong affinity between titanium and oxygen (O), resulting in elevated manufacturing costs during the refining, melting, and casting processes. The current work introduces a high-throughput technique that effectively reduces the oxygen content in molten titanium to a level suitable for structural material applications (1000 mass ppm, equivalent to 0.1 mass%). This technique aspires to streamline the mass production of titanium by seamlessly integrating the refining, melting, and casting processes. The developed method leverages the high affinity of rare-earth metals, such as yttrium (Y), for oxygen. This method utilizes the formation reaction of their oxyhalides (YOF) to directly remove oxygen from liquid titanium, resulting in titanium with a significantly reduced oxygen content of 200 mass ppm. This technique enables the direct conversion of titanium oxide feeds into low-oxygen titanium without requiring conversion into intermediate compounds. Additionally, this process offers a pathway for the upgrade recycling of high-oxygen-content titanium scrap directly into low-oxygen titanium. Consequently, this technology holds the potential to dramatically lower titanium production costs, thereby facilitating its more widespread utilization. Titanium has a strong affinity to oxygen, resulting in an increase in the manufacturing cost and complexity of the processes. Here the authors introduce a high-throughput technique using yttrium that can reduce the oxygen content in molten titanium to the level suitable for structural applications. [ABSTRACT FROM AUTHOR]

Aluminium metal foams offer low density (∼10–15% of bulk material) possessing cellular structure that ensures unique features with high stiffens, better energy absorption, thermal and acoustic properties. Selection of different foaming agents for preparing AA6061 foam samples are indeed an industrial relevance for better control over porosity and its dimensions, strengths (tensile, flexural and compression) useful for distinguished applications. Three foaming agents such as wax powder, magnesium hydroxide, and titanium hydride are selected with varying 3–9 weight percentage to prepare metal foams viz. powder metallurgy technique. For the prepared foam samples the percentage porosity, pore dimensions (maximum pore size, and equivalent diameter) and strengths were examined. Wax powder foaming agent resulted with a maximum strength in foam samples compared to magnesium hydroxide and titanium hydride. Scanning electron microscope with energy dispersive spectroscopy analysis revealed that there is no evidence of foreign elements and confirm uniform distribution of porosity in the foam samples. [ABSTRACT FROM AUTHOR]

The results of experimental studies on attenuating neutron and photon radiation in a nuclear reactor using a protective metal hydride composite are presented. The distribution profile of the dose and spatial energy is obtained for primary and secondary gamma radiation. It is shown that the dose of gamma radiation behind the protection is associated with capturing gamma rays generated in the initial layer of the material. Based on the results obtained, the calculation model of the experiment is verified in the two-dimensional geometry for the properties of the material protecting the reactor. The verification involves the discrete ordinate method based on the DORT package. Deviations between the calculated and experimental values of the fast neutron relaxation lengths do not exceed 5%. The same deviations obtained for gamma radiation are under 7%, which confirms the validity of the calculation technique and the potential to apply the data obtained to proceed with designing radiation protection based on the metal hydride composite. [ABSTRACT FROM AUTHOR]

The influence of a dispersed powder filler obtained by thermal synthesis from a mixture of 65% titanium hydride, 30% ferrosilicon, and 5% technical carbon powders, on the main physicomechanical properties of a polymer composite based on ED-20 epoxy diane oligomer, is investigated. The content of the filler varied in the range from 5 to 40 mass%. The introduction of the filler into the polymer composition leads to a noticeable increase in the main mechanical characteristics of the composite. Its maximum values at the dispersed component content of 10%, ensure an increase in bending strength in 1.6 times, and an impact toughness in 1.7 times compared to the original matrix. A further increase in the dispersed filler content in the composite composition to 20–40% leads to a decrease in fracture stresses, the level of which, however, still exceeds the strength of the original matrix phase. Composites with 5% filler demonstrate maximum values of adhesive strength and minimum values of residual stresses. When the content of dispersed filler increases by more than 5–10%, the formation of the dispersed particles conglomerates the number and size of which increase with the increase in the powder concentration in the mixture is observed in the composite structure. [ABSTRACT FROM AUTHOR]

The radiation shielding parameters such as effective atomic number, effective electron density, mean free path (MFP), half value layer (HVL) and tenth value layer (TVL) were calculated experimentally and theoretically for Boron Carbide(BC4), Boron nitride (BN), Boric acid (H3BO3), Iron boride (Fe2B), Lanthanum borate (BLaO3), Sodium borohydride (NaBH4), Borax (Na2H20B4O17), Titanium diboride (TiB2), and Zirconium diboride (ZrB2) compounds. In experimental measurements, the compounds were irradiated by 137Ba, 152Eu and 241Am radioactive gamma-ray sources. The theoretical results obtained with the help of the WinXCom computer program were compared with the experimental results and they were found to be in good agreement. Moreover, energy absorption buildup factor (EABF) and exposure buildup factor (EBF) values were calculated for compounds using the geometric progression (G.P.) fitting formula for the energy range of 0.015–15 MeV and penetration depth up to 40 mfp (mean free path). Buildup factors (EABF, EBF) increased with increasing penetration depth. In general, the buildup factors for all compounds formed a Gaussian curve and had the highest values in the energy range dominated by Compton scattering. As a result of the findings obtained in the study, it was seen that Lanthanum borate gave the best results in radiation shielding. [ABSTRACT FROM AUTHOR]

[Display omitted] The scientific paper presents studies of the radiation-protective features of a polymer composite material for protection against space radiation based on poly-tetra-fluoro-ethylene, Bi 2 O 3 bismuth oxide, WC tungsten carbide, B 4 C boron carbide, TiH 1.7 titanium hydride shot. The composite provides for a high degree of protection against ionizing radiation, including protection against exposure to secondary neutrons: macroscopic fast neutrons removal cross-section (E > 2 MeV) 0.1331–0.1414 cm−1, thermal-velocity neutrons removal cross-section (E < 0.4 eV), cm−1 0.1183–0.1257 cm−1. A shield made of the tailored composition of the proposed 6 cm thick polymer composite attenuates the intensity of neutron radiation by more than 50 % at energies from 0.1 to 5 MeV, in particular, the greatest attenuation of the neutron radiation intensity occurs at an energy of 0.1 MeV with a sharp increase in attenuation when passing through a 2 cm thick shield and complete absorption occurs passing through a 6 cm thick shield. This material can be used to protect astronauts and radio-electronic equipment from the effects of adverse or harmful space factors, including exposure to secondary neutrons, and this material can also be used to protect crews of ships with mobile nuclear reactors such as atomic submarines and nuclear-powered icebreakers. [ABSTRACT FROM AUTHOR]

[Objective] The rapid development of nuclear technology and the continuous expansion of nuclear energy applications have focused engineering research on the conceptual design and shielding calculations of advanced reactors. The development of third-generation advanced modular small reactors has elevated the requirements for the types of neutron-shielding materials, equipment quality, and compactness of design. For shielding, these materials must exhibit good neutron and y-ray slowing down and absorption performance and have excellent mechanical properties to ensure structural integrity during long-term operation. Traditional shielding materials mostly rely on simple high-hydrogen-content compounds, high-density metal, and boron-containing concrete materials. However, when shielding small solid-state reactors, they gradually exhibit shortcomings in physical and mechanical performances. Addressing the inadequacies in the design and application research of composite shielding solutions for current small solid-state reactors, lightweight materials with excellent composite shielding performance can effectively meet the radiation shielding needs in complex geometric structures and operational scenarios. [Methods] This study selected lightweight materials with excellent performance for a single-tube neutron radiation detection system and conducted relevant performance experiments. Theoretical values and experimental results were cross validated through uncertainty simulations. After a comprehensive comparison of the physical performances and processing costs of neutron slowing down and absorption materials, coupled with discussions on the feasibility of neutron-shielding experiments in an experimental environment, boron carbide, titanium hydride, and zirconium hydride were chosen as the shielding materials for this experiment. Special-sized containers were customized, and samples encapsulated in organic glass and PVC materials were prepared. Performance tests of the shielding materials were conducted by counting the number of neutrons at counter positions in the single-tube neutron radiation detection system. The experimental data, including counting averages (n/s), sample variance, and the characterized shielding effectiveness, were recorded, summarized, and analyzed in detail. Subsequently, the detection system was modeled using the independently developed reactor Monte Carlo code by the REAL team at Tsinghua University. Monte Carlo particle transport simulations were used to validate the consistency between experimental and theoretical data. [Results] The experimental results indicate the following findings: 1) The shielding enclosure device comprising PVC material has virtually no impact on background neutron counts, while the use of organic glass material leads to a substantial effect, reaching 5%-6%. 2) Under the experimental conditions, boron carbide exhibits a noticeable absorption effect on neutrons, with a 3 mm thickness already achieving a considerable absorption effect at nearly an order of magnitude. 3) Under equivalent experimental conditions, the shielding effectiveness of titanium hydride and zirconium hydride is unsubstantial. However, titanium hydride slightly outperforms zirconium hydride. This superiority is observed because, in hydrogen-containing materials, titanium hydride and zirconium hydride have the same proportion of hydrogen nuclei. Because of the slightly higher neutron absorption cross-section of titanium nuclei compared to zirconium nuclei, the absorption effect makes titanium hydride slightly better than zirconium hydride in overall shielding effectiveness. 4) The experimental data collected align well with Monte Carlo simulation calculations, indicating the correctness of the experimental approach in this study.[Conclusions] The data and conclusions obtained from this study on lightweight shielding materials with specific characteristics apply to other novel shielding systems and devices. The research indicates that under equivalent irradiation conditions, shielding effectiveness increases in the order of boron carbide, titanium hydride, and zirconium hydride. Simulations and experiments provide guidance and validation, establishing a solid theoretical foundation for introducing composite diffusive shielding materials into portable small nuclear power systems. [ABSTRACT FROM AUTHOR]

Machine learning interatomic potentials (MLIPs) enable accurate simulations of materials at scales beyond that accessible by ab initio methods and play an increasingly important role in the study and design of materials. However, MLIPs are only as accurate and robust as the data on which they are trained. Here, we present DImensionality-Reduced Encoded Clusters with sTratified (DIRECT) sampling as an approach to select a robust training set of structures from a large and complex configuration space. By applying DIRECT sampling on the Materials Project relaxation trajectories dataset with over one million structures and 89 elements, we develop an improved materials 3-body graph network (M3GNet) universal potential that extrapolates more reliably to unseen structures. We further show that molecular dynamics (MD) simulations with the M3GNet universal potential can be used instead of expensive ab initio MD to rapidly create a large configuration space for target systems. We combined this scheme with DIRECT sampling to develop a reliable moment tensor potential for titanium hydrides without the need for iterative augmentation of training structures. This work paves the way for robust high-throughput development of MLIPs across any compositional complexity. [ABSTRACT FROM AUTHOR]

Titanium and zirconium alloys are indispensable structural materials in many technical applications due to their unique mechanical and physicochemical properties. Titanium and zirconium belong to the fourth ("titanium") group, due to which one would expect them to exhibit a similar character of hydrogen permeability through alloys of these metals. The results of experiments on the hydrogen permeability of these alloys are compared and analyzed. It is revealed that the hydrogen permeation kinetics for both alloys is mainly determined by the low rate of surface processes and phase transformations, occurring as a result of increasing hydrogen concentration. It is shown that the hydrogen permeability method can be used to find the terminal solid solubility of hydrogen in metals. [ABSTRACT FROM AUTHOR]

Various foaming agents can be used to achieve foaming of the precursors obtained by using the powder metallurgy method. However, the thermal behavior of pure aluminum precursors with different foaming agents has been studied very little in recent times. For the production of aluminum foams with closed cells, 1 wt.% of calcium carbonate (CaCO3), titanium hydride (TiH2), heat-treated TiH2 and zirconium hydride (ZrH2) were used. The foaming capability of the compacted precursors was investigated at temperatures 700, 720 and 750 °C. CaCO3 and TiH2 showed the best foamability at all considered temperatures, while ZrH2 achieved relatively good foaming only at the highest temperature, 750 °C. Due to their low onset temperature of the decomposition compared to the melting point of the unalloyed aluminum, in hydride-based foaming agents the drainage occurred at the bottom part of the foam samples. Among the investigated foaming agents, precursors with heat-treated TiH2 had the worst foaming properties, while CaCO3 showed the best foamability without the occurrence of drainage. [ABSTRACT FROM AUTHOR]

In order to improve the explosion characteristics of emulsion explosives, titanium hydride was added to emulsion explosives to produce a new type of hydrogen storage emulsion explosives. Charges with different contents of titanium hydride were evaluated through underwater explosion experiments and detonation velocity tests. The tests on underwater explosion and detonation velocity reveal that compared to pure emulsion explosives, the detonation parameters of emulsion explosives containing titanium hydride showed a trend of first increasing and then decreasing. When the mass ratio of titanium hydride in the emulsion explosive is 1 % to 3 %, all detonation parameters have been improved to a certain extent. When the mass ratio of titanium hydride in the emulsion explosive is 3 % to 10 %, only part of the detonation parameters (specific impulse, specific shock energy, specific total energy and volume energy density) has been improved. The maximum increase of specific impulse, specific shock energy, specific total energy and volume energy density of emulsion explosive containing titanium hydride is 7.06 %, 8.95 %, 3.97 % and 8.22 %, respectively. Based on the analysis, it is evident that though powdered TiH2 participates in the detonation reaction process of the emulsion explosive, the majority of TiH2′s energy is released during the secondary reaction occurring after the detonation wave front. Therefore, the detonation performance of emulsion explosives can be effectively improved by adding a certain mass ratio of titanium hydride. [ABSTRACT FROM AUTHOR]

MgH 2 is a promising hydrogen storage material and its hydrogen desorption kinetics can be enhanced by introducing catalysts. To deeply understand synergetic effect of multiple phases on hydrogen desorption of MgH 2 , the formation mechanism of catalytic phases and their effect on hydrogen storage properties were studied in a MgH 2 - 5 wt% TiF 3 - 15 wt% NiCp 2 composite. The experimental results demonstrate that the nano-sized Mg 2 NiH 4 , TiH 2 and MgF 2 phases can be formed in situ after sample preparation and activation. The in situ formed phases provide a synergetic effect on hydrogen absorption and desorption during subsequent cycling, leading to the significant enhancement of hydrogen desorption kinetics and cycle durability. This work provides guidance for the design and preparation of novel Mg-based materials with excellent hydrogen storage properties. [Display omitted] • Mg 2 NiH 4 , TiH 2 and MgF 2 can be formed in MgH 2 - 5 wt% TiF 3 - 15 wt% NiCp 2 composite. • Mg 2 NiH 4 , TiH 2 and MgF 2 provide a synergetic effect on hydrogen desorption of MgH 2. • Dehydrogenation activation energy of MgH 2 -TiF 3 -NiCp 2 composite is 76.2 kJ mol−1. • MgH 2 -TiF 3 -NiCp 2 composite has a capacity retention rate of 91% after thirty cycles. [ABSTRACT FROM AUTHOR]

Experimental hydrogen loadings in titanium thin films were compared to the Mintz-Bloch model. 500 nm titanium thin films were deposited with an electron-beam evaporator onto sapphire substrates and were capped with a 10 nm palladium thin film. The titanium films were loaded with hydrogen in a custom Sievert apparatus where the pressure drop showed full hydriding at a hydrogen pressure of 2 bar and loading temperatures of 100 °C, 150 °C, 200 °C and 250 °C. Comparisons of X-ray diffractions of loaded and unloaded films showed the presence of titanium hydride in loaded films. The experimental loadings were compared to the Mintz-Bloch model where the Mintz-Bloch model overpredicted experimental loadings. This was due to the Mintz-Bloch assuming that hydride forms immediately upon hydrogen exposure in the metal. However, the difference between the experimental loading kinetics and Mintz-Bloch model was reduced as loading temperatures increased until the temperature reached 250 °C where some titanium hydride outgassing occurred. • Hydrogen loading of titanium thin films was successfully demonstrated at 100 °C, 150 °C, 200 °C, and 250 °C. • Pressure drops from Sievert apparatus show hydrogen absorption of stoichiometric ratio of 2 hydrogen atoms per titanium atom. • Hydrogen absorption in titanium was confirmed with X-ray diffraction of titanium hydride peak. • Loading kinetics of titanium films compared to Mintz-Bloch model and showed good correlation. [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) [ABSTRACT FROM AUTHOR]

The need for the transition to carbon-free energy and the introduction of hydrogen energy technologies as its key element is substantiated. The main issues related to hydrogen energy materials and systems, including technologies for the production, storage, transportation, and use of hydrogen are considered. The application areas of metal hydrides as promising materials for hydrogen energy technologies are presented. Prospects for the commercialization of hydrogen and metal hydride technologies are discussed, including those using cheap hydride-forming materials based on titanium–iron alloys. [ABSTRACT FROM AUTHOR]

The proton exchange membrane electrolysis cell (PEMEC) is a green and efficient method for producing hydrogen. The flow field structure is a critical factor affecting the performance of electrolysis. However, conventional processing of flow channels is complex and expensive, a novel PEMEC structure utilizing three-dimensional titanium meshes as flow distributors instead of flow channels is proposed. It is found to exhibit higher current density, pressure, hydrogen concentration, and lower temperature than the traditional parallel flow fields. The current density is improved by 88.2 mA/cm2 and the energy consumption is reduced by 0.15 kW h N−1·m−3 at 1.9 V. Based on the uniformity index, the new structure is found to improve the current and temperature uniformity by 20.6% and 13.4%, respectively, when compared to the parallel flow field structure. Additionally, the physical properties of the mesh layers are studied in terms of their influence on electrolysis performance. The increase in porosity and decrease in thickness can enhance the performance of the cell. The results show that a structure with titanium meshes is more beneficial for improving the heat and mass transfer performance and optimizing uniform distribution than the parallel channels, which provides a new direction for the design of electrolysis cell structures. • A novel PEMEC structure with Ti meshes as flow distributors is proposed. • The new structure improves current and temperature uniformity by 20.6% and 13.4%, respectively. • The energy consumption is reduced by 0.09 kW h N−1·m−3 at 1.7 V. • Increasing porosity and decreasing thickness of mesh layers can improve the performance. [ABSTRACT FROM AUTHOR]

Recently, manufacturing of metallic titanium ingots based on a thermal decomposition process using titanium disulfide TiS2 as the intermediate product with a significantly lower decomposition temperature of approximately 4000K was reported. However, this process involves a carbothermic reaction for preparing the intermediate product. Carbonic acid gas, a cause of global warming, was generated, and the process is inadequate from the viewpoint of environmental protection. In the present study, a reaction process without the generation of carbonic acid gas was used. Dilute hydrogen-mixed argon gas was used for the synthesis of the intermediate product. The phases of the synthesized intermediate products were investigated using X-ray diffraction and were matched to several titanium sulfide phases, such as TiS, and Ti2S3, which have a higher titanium ratio than the product, TiS2, synthesized by carbothermic reaction. The thermodynamic conditions of the synthesis process, such as the partial pressures of oxygen and sulfur, were also predicted from the product phases. [ABSTRACT FROM AUTHOR]

Microwave loss in superconducting TiN films is attributed to two-level systems in various interfaces arising in part from oxidation and microfabrication-induced damage. Atomic layer etching (ALE) is an emerging subtractive fabrication method which is capable of etching with angstrom-scale etch depth control and potentially less damage. However, while ALE processes for TiN have been reported, they either employ HF vapor, incurring practical complications, or the etch rate lacks the desired control. Furthermore, the superconducting characteristics of the etched films have not been characterized. Here, we report an isotropic plasma-thermal TiN ALE process consisting of sequential exposures to molecular oxygen and an SF 6 /H 2 plasma. For certain ratios of SF 6 :H 2 flow rates, we observe selective etching of TiO 2 over TiN, enabling self-limiting etching within a cycle. Etch rates were measured to vary from 1.1 Å/cycle at 150 ° C to 3.2 Å/cycle at 350 ° C using ex situ ellipsometry. We demonstrate that the superconducting critical temperature of the etched film does not decrease beyond that expected from the decrease in film thickness, highlighting the low-damage nature of the process. These findings have relevance for applications of TiN in microwave kinetic inductance detectors and superconducting qubits. [ABSTRACT FROM AUTHOR]

Composite materials made from aluminum foam are increasingly used in aerospace and automotive industries due to their low density, high energy absorption capacity, and corrosion resistance. Additive manufacturing processes offer several advantages over conventional manufacturing methods, such as the ability to produce significantly more geometrically complex components without the need for expensive tooling. Direct Energy Deposition processes like Wire Arc Additive Manufacturing (WAAM) enable the additive production of near-net-shape components at high build rates. This paper presents a technology for producing aluminum foam structures using WAAM. This paper’s focus is on the development of welding wires that are mixed with a foaming agent (TiH2) and produce a foamed weld metal as well as their processing using MIG welding technology.

The effects of the secondary processes of Hot Isostatic Pressing (HIP) at 920 °C and Heat Treatment (HT) at 1000 °C of Electron Beam-Melted (EBM) Ti–6Al–4V alloy on the microstructure and hydrogen embrittlement (HE) after electrochemical hydrogen charging (EC) were investigated. Comprehensive characterization, including microstructural analysis, X-ray diffraction (XRD), thermal desorption analysis, and mechanical testing, was conducted. After HIP, the β-phase morphology changed from discontinuous Widmanstätten to a more continuous structure, 10 times and ~1.5 times larger in length and width, respectively. Following HT, the β-phase morphology changed to a continuous “web-like” structure, ~4.5 times larger in width. Despite similar mechanical behavior in their non-hydrogenated state, the post-treated alloys exhibit increased susceptibility to HE due to enhanced hydrogen penetration into the bulk. It is shown that hydrogen content in the samples’ bulk is inversely dependent on surface hydride content. It is therefore concluded that the formed hydride surface layer is crucial for inhibiting further hydrogen penetration and adsorption into the bulk and thus for reducing HE susceptibility. The lack of a hydride surface layer in the samples subject to HIP and HT highlights the importance of choosing secondary treatment process parameters that will not increase the continuous β-phase morphology of EBM Ti–6Al–4V alloys in applications that involve electrochemical hydrogen environments.

The fracture mechanism of hydrogen charged Ti–6Al–4V has been investigated through a multianalytical approach. The difference in hydrogen solubility between β phase (high solubility) and α phase (low) governs the formation and growth pattern of titanium hydrides, and determine the fracture mode of Ti–6Al–4V. Depending on the hydrogen charging extent, the penetration of hydrogen and distribution of hydrides can be divided into three stages. In the initial stage hydrogen diffuses mainly into the β phase, as judged from its increase in Volta potential, and with no hydrides formed. Failure analysis after tensile tests exhibits plastic behavior and a fracture surface with mainly dimples. In the subsequent transition stage, hydrides are formed at the α/β interfaces and along α grain boundaries. More initial cracks occur in the brittle hydrides and the fracture surface transforms from dimple to quasi-cleavage. In the final stage a layer of uniformly distributed hydride is produced on the surface and within the α phase. Supported by nanoindentation measurements, the plasticity of the charged sample diminishes with hydrogen charging time, and an intergranular-transgranular mixed fracture is observed. Overall, the study forms clear evidence that the distribution and cracks of hydrides influence the fracture mode of the Ti-6A-4V alloy. • Hydrides form at α/β interface, grow along α grain boundaries, and occupy α grains. • Cracks initiate and propagate through soft-brittle hydrides. • The presence and distribution of hydrides determine the mode of fractures. • Hydrogen permeation increases the Volta potential difference between β and α phases. [ABSTRACT FROM AUTHOR]

Magnéli phase titanium oxides, also called titanium sub-oxides (TinO2n−1, 4 < n < 9), are a series of electrically conducting ceramic materials. The synthesis and applications of these materials have recently attracted tremendous attention because of their applications in a number of existing and emerging areas. Titanium sub-oxides are generally synthesized through the reduction of titanium dioxide using hydrogen, carbon, metals or metal hydrides as reduction agents. More recently, the synthesis of nanostructured titanium sub-oxides has been making progress through optimizing thermal reduction processes or using new titanium-containing precursors. Titanium sub-oxides have attractive properties such as electrical conductivity, corrosion resistance and optical properties. Titanium sub-oxides have played important roles in a number of areas such as conducting materials, fuel cells and organic degradation. Titanium sub-oxides also show promising applications in batteries, solar energy, coatings and electronic and optoelectronic devices. Titanium sub-oxides are expected to become more important materials in the future. In this review, the recent progress in the synthesis methods and applications of titanium sub-oxides in the existing and emerging areas are reviewed. [ABSTRACT FROM AUTHOR]

This work presents a new method for synthesizing the widely used near-α Ti–8Al–1Mo–1V alloy. To this end, we sequentially used two methods: metal hydrides were synthesized by Self-propagating High-temperature Synthesis (SHS) method, and the said alloy was synthesized by Hydride cycle (HC) method, using the SHS-produced hydrides. The main point of the SHS method is to use of heat of the exothermic reaction, locally initiated in a thin layer of metal powder. The gist of the HC method, developed by us, is to use transition metal hydrides as starting materials for alloy synthesis. The approaches, elaborated in the present work, resulted in the synthesis of Ti–8Al–1Mo–1V alloy, consisting of 94 to 95.7 wt pct α-phase and 6 to 4.3 wt pct β-phase. The formation of the alloy proceeded according to the solid-phase mechanism. The alloy without crushing interacted with hydrogen in the SHS mode, forming a reversible hydride (Ti–8Al–1Mo–1V)H1.28. Hydrogen enhanced the fragility of the hydride and made it possible to grind it to powder with particle sizes under 3 microns (even down to 100 nm and less) within 30 to 40 minutes, without contamination of the particle surfaces. Simultaneously, the presence of hydrogen in the crystal lattice of alloy hydride increased its plasticity. Compacting the hydride to the designed shape and the following by sintering dehydrogenation at temperature close to the hydride decomposition temperature, allowed us to get a product of a required form. The elaborated HC method for synthesizing of the near-α-alloy has significant advantages over the traditional methods: low temperature (1000 °C instead of 1800 °C to 2600 °C), short duration (0.5 to 1 hour instead of dozens of hours), one stage, ecologically friendly, energy-saving process, solid-phase mechanism without melting, etc. The elaborated HC methods for the synthesis of near-α Ti–8Al–1Mo–1V alloy and the synthesis of its hydride (Ti–8Al–1Mo–1V)H1.28 by the SHS method can be of commercial and industrial interest. [ABSTRACT FROM AUTHOR]

TiO2 is a typical anti‐ultraviolet agent in sunscreen cream, but it suffers from a lack of anti‐oxidant activity for scavenging reactive oxygen species. Other traditional sunscreen ingredients, such as C60 and ferulic acid, have moderate antioxidant and UV protection capabilities, and the products do not provide further UV protection. Herein, titanium hydride (TiH1.97) particles with dual functions of anti‐oxidant and anti‐ultraviolet are presented as an active material to remove the highly oxidizing and harmful hydroxide free radicals from the skin surface. Owing to the active hydrogen in TiH2, it shows great potential to eliminate hydroxyl radicals, and the rate is roughly proportional to the exposed surface area (50% /20 min). Together with the biocompatibility of the in situ formed TiO2, which has a strong ability to absorb ultraviolet light during OH radical scavenging. At the same time, adding titanium hydride to sunscreen also enhances sun protection. The SPF value of sunscreen containing 1% titanium hydride and 20% titanium dioxide can reach 31.8, which exceeds the 20% titanium dioxide (15) by more than twofold. Therefore, titanium hydride with anti‐ultraviolet and antioxidant functions can be regarded as a promising and safe ingredient for sunscreen cream. [ABSTRACT FROM AUTHOR]

This study focuses on titanium dioxide (TiO2) nanotubes on solid substrates, which may find wide applications as photocatalysts and catalysts. To address the need for more stable and active electrocatalysts with reduced noble rretal content, the study explores Ti. Oj sub oxi des as promising substrates for the electrocatalysts. Notably, the addition of water in the fluoride-containing electrolyte plays a critical role in shaping the moiphology of TiO2 nanotubes, leading to the fonnation of ordered structures under specific water concentration conditions. The study also examines the effects of platinum and palladium deposition on TiO2 nanotubes, enhancing their surface crystallinity and structural arrangement. The presence of an unidentified phase, possibly titanium hydride, is observed in certain samples. The findings highlight the potential of TiO2 nanotubes as efficient electrocatalysts and the influence of water content and substrate choice on their properties, opening up new avenues for advanced applications in various fields. [ABSTRACT FROM AUTHOR]

The suppression effects of melamine polyphosphate, titanium dioxide and melamine cyanurate powders on titanium hydride dust explosions were studied using a 1.2 L standard Hartmann tube system, a 20-L spherical vessel testing system, a simultaneous thermal analyzer and a field emission scanning electron microscope. The experimental results showed that the three solid suppressants could effectively decrease the explosion parameters such as flame luminescence intensity, flame propagation velocity and maximum explosion pressure, et al. Because of the different suppression characteristics of the suppressants, their suppression effects on the particles combustion temperatures were significantly different. To completely suppress the dust explosion of titanium hydride, the inerting ratio of the melamine polyphosphate powders was the smallest when compared with those of the titanium dioxide and melamine cyanurate powders. In addition, the field emission scanning electron microscope was used to analyze the residues of a dust explosion. The testing results showed that the thermal decomposition residues of melamine polyphosphate powders were coating on the surface of the unburned titanium hydride particles to make them lose reactivity, that was why the suppression effect of melamine polyphosphate powders was the most effective when compared with titanium dioxide and melamine cyanurate powders. [Display omitted] [ABSTRACT FROM AUTHOR]

Superconductivity in highly pressurized hydrides has become the primary direction for the exploration of the fundamental upper limit of the superconducting transition temperature, T c , after Drozdov et al. (Nature2015, 525, 73) discovered a superconducting state with T c = 203   K in highly compressed sulfur hydride. To date, several dozen high-temperature superconducting polyhydrides have been discovered and, in addition, it was recently reported that highly compressed titanium and scandium exhibit record-high T c (up to 36 K). This exceeded the T c = 9.2   K value of niobium many times over, which was the record-high   T c ambient pressure metallic superconductor. Here, we analyzed the experimental data for the recently discovered high-pressure superconductors (which exhibit high transition temperatures within their classes): elemental titanium (Zhang et al., Nature Communications 2022; Liu et al., Phys. Rev. B 2022), T a H 3 (He et al., Chinese Phys. Lett. 2023), L a B e H 8 (Song et al., Phys. Rev. Lett. 2023), black phosphorous (Li et al., Proc. Natl. Acad. Sci. 2018; Jin et al., arXiv 2023), and violet (Wu et al., arXiv 2023) phosphorous to reveal the nonadiabaticity strength constant T θ T F (where T θ is the Debye temperature, and T F the Fermi temperature) in these superconductors. The analysis showed that the δ -phase of titanium and black phosphorous exhibits T θ T F scores that are nearly identical to those associated with A15 superconductors, while the studied hydrides and violet phosphorous exhibit constants in the same ballpark as those of H 3 S and L a H 10 . [ABSTRACT FROM AUTHOR]

We introduce in this work a unique parameter for the quantitative assessment of the intrinsic strength of the π interaction between two monomers forming a complex. The new parameter is a local intermonomer stretching force constant, based on the local mode theory, originally developed by Konkoli and Cremer, and derived from the set of nine possible intermonomer normal vibrational modes. The new local force constant was applied to a diverse set of more than 70 molecular complexes, which was divided into four groups. Group 1 includes atoms, ions, and small molecules interacting with benzene and substituted benzenes. Group 2 includes transition metal hydrides and oxides interacting with benzene while Group 3 involves ferrocenes, chromocenes, and titanium sandwich compounds. Group 4 presents an extension to oxygen π–hole interactions in comparison with in-plane hydrogen bonding. We found that the strength of the π interactions in these diverse molecular complexes can vary from weak interactions with predominantly electrostatic character, found, e.g., for argon–benzene complexes, to strong interactions with a substantial covalent nature, found, e.g., for ferrocenes; all being seamlessly described and compared with the new intermonomer local mode force constant, which also outperforms other descriptors such as an averaged force constant or a force constant guided by the electron density bond paths. We hope that our findings will inspire the community to apply the new parameter also to other intermonomer π interactions, enriching in this way the broad field of organometallic chemistry with a new efficient assessment tool. [ABSTRACT FROM AUTHOR]

The use of NaAlH 4 as a practical hydrogen storage material has seen extensive progress. However, it is still difficult to control the hydrogen storage properties of NaAlH 4 and in particular its hydrogen thermodynamics. Herein, we demonstrate the potential of core-shell NaAlH 4 @Ti nanostructures in altering the hydrogen storage properties of NaAlH 4. To this aim, a facile solvent evaporation method was developed to enable the making of freestanding NaAlH 4 nanoparticles and their individual encapsulation within a Ti shell. These core-shell nanostructures enabled: (i) an effective confining environment for NaAlH 4 and its dehydrogenation products, and (b) fast hydrogen kinetics due to a weakening of the Al–H bond and the shorter diffusion lengths. At 180 °C, a reversible hydrogen storage capacity of 4.4 mass% was observed. More remarkably, this core-shell approach enabled a shift in the equilibrium plateau pressure, therefore demonstrating the possibility to control the hydrogen thermodynamics of NaAlH 4 at the nanoscale. [Display omitted] • Core-shell NaAlH 4 @Ti nanostructures have been successfully synthesized. • This enables fast NaAlH 4 hydrogen kinetics and a reversible hydrogen storage capacity of 4.4 mass%. • This also enables a shift in the plateau pressure and control over the hydrogen thermodynamics of NaAlH 4. [ABSTRACT FROM AUTHOR]

The attenuation of neutron radiation and the accompanying gamma radiation from a research reactor by means of shielding filled with metal hydride (using cement binder) is studied experimentally. The energy distribution of the neutrons and gamma radiation in the material is studied. The contribution of secondary gamma quanta to the total dose rate beyond the shielding is determined. [ABSTRACT FROM AUTHOR]

The surface structures and relative stabilities of low-miller-index surfaces of γ-TiH and γ-TiH2 have been investigated as a direct function of environmental conditions (hydrogen partial pressure pH2 and temperature T), using the first-principles thermodynamic calculations. The results were used to construct the surface phase diagrams for a wide pH2 range at T = 300 and 900 K. The γ-TiH surfaces tend to be dominated by the non-stoichiometric (110) at low pH2 values, and the most energy-favored surface termination would change from the 110-ns-2Ti1H to the 110-ns-2Ti2H and then to the 110-ns-2Ti4H as pH2 increases. For pH2 > e−43.6 at 300 K (or pH2 > e−2.5 at 900 K), γ-TiH can no longer be stable but have the tendency to transform into γ-TiH2, by consistently absorbing H from the gaseous environment. The γ-TiH2 surfaces tend to be dominated by the stoichiometric (111) facet with the 111-stoi-2H termination and with a surface energy of 1.31 J/m2. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A359 aluminum alloy composite containing 20 vol. % silicon carbide particles was remelted, and 100-mm diameter foam ingots were prepared using 0.75 wt. % of titanium hydride (TiH2). Three identical experiments each were carried out at two foaming temperatures (640 and 660 °C) to check the reproducibility of the cell structure and foam properties. Foams made at 640 °C were reproducible in terms of foam expansion, cell size and cell size variation along the ingot height. The property scatter, evaluated in terms of relative standard deviation, is similar for density and modulus of the foam. For compressive plastic strength, the scatter is double than for density. The density and mechanical properties are reproducible within these scatters. Foams prepared at 660 °C, on the other hand, suffered from liquid foam collapse during solidification and hence couldn't be qualified for detailed study of reproducibility. The collapse resulted in distortion of the foam ingot and elongated cell structures in other parts. However, the cell size and mechanical properties in the un-distorted region are comparable with those foamed at 640 °C. Overall, good quality cell structure and consistent mechanical properties could be obtained in foams processed at 640 °C. [ABSTRACT FROM AUTHOR]

MAX phases are new type of easily machinable cermets, demanded in modern materials science as construction materials. One of the most widely studied and promising representatives of the titanium-based MAX phases are hexagonal Ti 2 AlC and Ti 3 AlC 2. Current methods of their synthesis are unsuitable for their mass production. The creation and development of new methods and technologies for their producing are urgent tasks of materials science. The modern technologies are required providing high quality and productivity, cost-effective, environmentally friendly and easily scaled methods. In 2007, in our Laboratory of High-Temperature Synthesis of the IChPh of Armenian NAS, the Hydride Cycle method (HC) for synthesis of refractory alloys and intermetallic compounds was elaborated. The gist of this method is the use of the synthesized by Self-propagating High-temperature Synthesis mode (SHS) transition metal hydrides as starting materials. In the present work, for the first time, the HC method was applied in the synthesis of Ti 2 AlC and Ti 3 AlC 2 MAX phases. Preliminarily, HCP TiC 0.45 H 1.07÷1.17 , FCC TiC 0.5 H 0.22÷0.73 and TiC 0.67 H 0.31-0.39 titanium carbohydrides were synthesized in the SHS mode and used as starting reagents. The present work was set to study the effect on the phase composition and structure of the synthesized MAX phases of conditions of HC. The analysis methods, used to certify the synthesized MAX phases, were: chemical, differential-thermal, X-ray phase. The microstructures of the samples were snapshot on SEM Prisma E scanning electron microscope. The work resulted in the synthesis in HC of single-phase Ti 2 AlC and Ti 3 AlC 2 MAX phases with unit cell parameters [а = 3.0553; c = 13.6459; c/a = 4.466; P6 3 /mmc] and [a = 3.0552; c = 18.7396; c/a = 6.132], respectively. This work demonstrated advantages of HC over the traditional methods of MAX phases synthesis. [ABSTRACT FROM AUTHOR]