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In recent developments, Cu–Cr–Nb alloys have emerged as promising materials offering a desirable balance between mechanical properties and electrical conductivity, rendering them suitable for intricate high heat flux applications. However, the laser additive manufacturing of Cu–Cr–Nb alloys has encountered notable challenges, primarily stemming from limitations associated with Cu–Cr–Nb alloy powders. Recognizing the pivotal role of powder feedstock in additive manufacturing, this study exerts the utilization of ball milling techniques to tackle pertinent challenges. Specifically, a kind of powder obtained by mechanical ball milling of elemental powders of Cu, Cr and Nb is employed to fabricate Cu–Cr–Nb raw materials, which exhibits a distinctive sesame ball structure and effectively mitigates the inherent high reflectivity of Cu powder. The resulting milled powder represents a notable departure from the conventional reliance on argon gas atomization for Cu–Cr–Nb alloy powder production. Then the study encompasses the fabrication of five distinct Cu–Cr–Nb bulk alloys, ranging from Cu–1Cr–0.5Nb to Cu–12Cr–6Nb, using laser directed energy deposition. The as-printed Cu–Cr–Nb alloys exhibit commendable density, surpassing 99% based on visual analysis, and demonstrate mechanical properties akin to casts achieved through traditional melting and powder metallurgy methods. Notably, Cr2Nb particles were observed within all bulk alloys, with their size increasing proportionally with the Cr + Nb content. Tensile strength demonstrated a positive correlation with Cr + Nb content, while elongation and conductivity exhibited an inverse relationship. These findings hold considerable promise for advancing the utilization of Cu–Cr–Nb alloys in various applications requiring tailored performance characteristics. [ABSTRACT FROM AUTHOR]

To ensure the safety and efficiency of hydrogen isotopes in the storage and delivery system (SDS), Zr-Mn-V based hydrogen isotopes storage alloys were prepared by induction levitation melting technique under Ar atmosphere. The effects of modification for Zr-Mn-V alloy of ZrMn 2-x V x (x = 0, 0.4, 0.6, 0.8) and ZrMn 1.4-y V 0.6 (y = 0, 0.2, 0.4) on microstructure, hydriding kinetics, de-/hydrogenation thermodynamics, cycling stability and anti-disproportionation performance were systematically investigated. The results show that all alloys contain a main phase of ZrMn 2 and little impure phase. Crucially, the lattice parameters of ZrMn 2 phase increase after V substitution, as well as Mn decrease, leading the equilibrium pressure of dehydrogenation significantly decreases from 2.931 bar (ZrMn 2 -H) to 0.080 bar (ZrMn 1.2 V 0.6 -H) at 200 °C, and the corresponding enthalpy changes from 43.29 to 60.38 kJ mol−1 H 2. Compared with ZrCo, ZrMn 1.2 V 0.6 exhibits outstanding stability with 1.63 wt% during 20 cycles and scarcely losing on capacity through the anti-disproportionation measurement under the simulated SDS environment. Consequently, considering all the performances of ZrMn 1.2 V 0.6 sample, it could be an alternative material for hydrogen isotopes storage and delivery to be applied in SDS. • The lattice parameters of ZrMn 2 phase increases with increasing of V and reducing of Mn. • Zr-Mn-V based samples show excellent hydriding kinetics at room temperature. • The hydrogenation equilibrium pressure decreases with increasing of V and reducing of Mn. • ZrMn 1.2 V 0.6 exhibits outstanding cycling stability and anti-disproportionation performance. [ABSTRACT FROM AUTHOR]

Hydrogen is the ideal green fuel and carbon-neutral energy carrier alternative to nonrenewable fuel sources. The high construction cost of hydrogen refueling stations has become one of the limitations to the further promotion and application of hydrogen energy. To realize 8–22 MPa hydrogen compression under mild conditions, the low cost Ti 0.95 Zr 0.07 Cr 1.7- x Mn 0.3 Fe x (x = 0–0.5) alloys were designed and prepared by magnetic levitation melting in this work. The effect of Fe on Cr substitution on the microstructure and hydrogen storage properties of the alloy has been systematically investigated. With the increase of Fe substitution for Cr, all the alloys maintain a single C14 Laves phase, the thermodynamic plateau curve broadens and rises, while the hydrogen storage capacity diminishes slightly. For a better description of the thermodynamic properties of alloys at high temperatures as the function of temperature, a non-linear Van't Hoff fitting is introduced with satisfactory prediction. On account of significant Fe substitution for Cr, the unit cell shrinks and the interstitial size of alloy decreases, an optimal alloying constituent, Ti 0.95 Zr 0.07 Cr 1.3 Mn 0.3 Fe 0.4 , has been proposed and experimentally proved for the first time. This alloy exhibits the best overall performances and the plateau pressure is respectively 5.74 MPa for hydrogenation at 283 K and 25.97 MPa for dehydrogenation at 353 K without apparent hysteresis phenomenon. The hydrogen storage capacity is 1.59 wt% within 3 min and dehydrogenation enthalpy is 21.20 kJ/mol H 2. This study provides a comprehensive insight into the low-cost hydrogen storage alloy design and application on quick response and high cycle stability metal hydride hydrogen compressors. [Display omitted] • Ti 0.95 Zr 0.07 Cr 1.7- x Mn 0.3 Fe x alloys were explored to realize 8–22 MPa hydrogen compression. • The effects of Fe on Cr substitution on hydrogen compression properties were revealed. • A non-linear Van't Hoff fitting was developed to forecast high hydrogen compression property. [ABSTRACT FROM AUTHOR]

Hysteresis of hydrogen storage alloys essentially hinders the compressibility and operation efficiency of metal hydride hydrogen compressors. In this work, minor Al additive was added into Ti–Cr based hydrogen compression alloys through induction levitation melting, and the apparent hysteresis was successfully ameliorated. The XRD and SEM results indicate homogeneous element distribution of a main C14 Laves phase of Ti 0.96 Zr 0.06 Cr 1.0 Mn 0.6 Fe 0.4 Al x (x = 0, 0.01, 0.02, 0.04, 0.08) alloys, and vanishing of a minor oxide phase in case the Al additive is introduced. As Al stoichiometry increases in the alloys, the hydrogenation plateau decreases obviously but the dehydrogenation plateau hardly changes. Meanwhile, the hydrogen capacity ascends initially but descends slightly. Additionally, no severe performance degradation is induced. The mechanism for overall performance improvement can be concluded as dual functions of Al additive: one can be oxide reduction of other elements during melting determined by XPS and ICP, and the other can be partial Al substitution for the B-side elements, leading to relieved deformation energy surrounding the vacant Al-containing interstitials. As to hydrogenation kinetics, the alloys exhibit accelerated hydrogenation rate with increased Al stoichiometry due to decreased activation energy and hydrogenation plateau. Furthermore, the first-principles calculation results indicate random Al substitution for the B-side atoms, and anisotropic expansion of the unit cell can be attributed to Al substitution at 6h sites. This work reveals a simple and effective way to enhance hydrogen storage performance of Ti–Cr based alloys. [Display omitted] • Influence of minor Al additive in Ti–Zr–Cr–Mn–Fe based alloys is investigated. • Hysteresis is remarkably modified by Al additive with overall enhanced performance. • Reduction and substitution dual-effect of Al is key mechanism for modification. • Results of first-principles calculation indicate random Al substitution at B-sites. • Optimum stoichiometry of Al additive should be 0.01–0.04 in the studied alloys. [ABSTRACT FROM AUTHOR]

ZrCo alloy has been considered as one of most promising materials for handling hydrogen isotopes in International Thermonuclear Experimental Reactor (ITER), due to its remarkable superiority in terms of de-/hydriding kinetics, thermodynamics, 3He trapping and security. However, hydrogen storage performances of ZrCo alloy demands further ameliorating to accommodate the complex working condition in storage and delivery system (SDS), involving comparable kinetics to depleted uranium (DU), low desorption temperature, stable 3He trapping ability and high reversible capacity. To solve these challenges, various modification strategies concerning multiple alloying, process regulation, surface decoration and bed optimization have been developed over the past decades. In this review, we present a comprehensive survey on the previous advances in improving these four aspects of hydrogen storage performances for ZrCo-based alloys. Firstly, basic hydrogen storage characteristics of ZrCo alloy are introduced. Then, the impacts of different modification strategies on de-/hydriding rates, desorption temperature, 3He trapping ability and cycling stability are respectively outlined based on theoretical calculation and experimental results. Meanwhile, alloying is declared as the most effective improvement avenue and the specific function of each element substitution is systematically provided. Specifically, lattice modulation for constructing stable isostructural de-/hydrogenation transformation shows the most effective impact on the improvement of cycling stability and anti-disproportionation property in ZrCo-based alloy by multiple alloying. Finally, the remaining challenges and further development of ZrCo-based hydrogen isotopes storage materials henceforth will be prospected. [Display omitted] • Overall modification strategies on ZrCo-based hydrogen storage alloys are reviewed. • Specific tuning impacts are analysed, wherein alloying is declared as most effective. • Remained challenges and further development direction are prospected. [ABSTRACT FROM AUTHOR]

Abstract: The influence of Fe content on the microstructure and hydrogen storage properties of Ti16Zr5Cr22V57−xFex (x = 2–8) alloys was investigated systematically. The results show that all alloys consist of a BCC main phase and a small amount of C14 Laves secondary phase. The crystal lattice parameters of the BCC main phase in the alloys decrease with the increase of the Fe content. Under moderate conditions, all the alloys have good activation behaviors and hydriding/dehydriding kinetics. As the x increases, the hydrogen desorption plateau pressure of the alloys increases consequently. Among the studied alloys, Ti16Zr5Cr22V55Fe2 alloy has suitable hydrogen desorption plateau pressures indicated by the middle value of pressure range. (0.1–1 MPa) at 298 K and the best overall hydrogen storage properties. [ABSTRACT FROM AUTHOR]

The hydrogen storage properties and microstructures of Ti-doped complex hydrides prepared by hydrogenation of ball-milled NaH/Al mixture with mol% Ti powder were investigated. It is found that hydrogen as ball-milling atmosphere is better than argon. The reversible hydrogen storage properties improve with increasing Ti content. As the milling time ( extends from 1 to 24h, the hydrogen desorption capacity increases first and then decreases, and reaches a maximum capacity of 4.25wt% at . The catalytic mechanism for hydrogen storage behavior of Ti-doped is attributed to the presence of active small and TiAl particles, which are scattered on the surface of much larger (NaH/Al) globelets, acting as the catalytic active sites for the complex compound and playing an important catalytic role in the hydriding-dehydriding process. [Copyright &y& Elsevier]

Abstract: Amorphous 2Mg–Fe+ x wt.% Ni alloys were synthesized by mechanical alloying of Mg and Fe elemental powders. Two kinds of ball-milling atmospheres, namely, (1) under argon and (2) first under argon and then in tetrahydrofuran (THF), were examined in this study. The effects of the Ni addition and ball-milling time and atmosphere on the microstructure and electrochemical properties of the prepared alloys have been investigated systematically. The results show that the ball-milled (2Mg–Fe) nickel-free mixture still maintains Mg and Fe elemental phases, and its discharge capacity is only 19.2mAhg−1. The Ni powder addition is advantageous for the formation of Mg–Fe amorphous structure and for the improvement of the electrochemical properties of the alloys. For the alloys milled under argon, with the Ni content x increasing, the discharge capacity of the alloys increases first and then decreases, and reaches a maximum value of 455.3mAhg−1 as x =100. With the milling-time extending, the discharge capacity of the alloy increases first and then decreases too. For the alloys milled under argon and then in THF, the alloys exhibit higher degree of amorphorization, bigger specific surface area and more active surfaces, and thus have better electrochemical properties than those milled under argon. With the Ni increasing, the discharge capacity increases from 249.7mAhg−1 (x =50) to 565.2mAhg−1 (x =150) and then decreases to 497.9mAhg−1 (x =200), and the exchange current density I 0 increases from 104.8mAg−1 (x =50) to 251.1mAg−1 (x =200), which is consistent with the variation of the HRD of the alloy electrodes in the investigation range. [Copyright &y& Elsevier]

Hydrogen isotope (deuterium and tritium) as a special form of hydrogen energy, its storage in an efficient and safe way has been paid more and more attention by researchers in recent years. ZrCo alloy is regarding as the one and only promising material for large-scale storage of hydrogen isotope. However, poor cycle life and inferior capacity retention restrict its engineering application. Herein, we propose a co-substitution strategy of Nb (for Zr) and Ni (for Co) in ZrCo alloy to overcome the defects. Significantly, Zr 0.8 Nb 0.2 Co 0.8 Ni 0.2 alloy exhibits ultralong cycle life (97.6% retention) and remarkable capacity (2.42 H (f. u.)) in 100 cycles, which far exceeds all existing hydrogen isotope storage alloys (Pd, U and other ZrCo-based alloys). These outstanding performances are entirely revealed from two aspects: stable homogeneous structural phase transformation process of parent structure (Zr 0.8 Nb 0.2 Co 0.8 Ni 0.2 H 0.3 -B33 ↔ Zr 0.8 Nb 0.2 Co 0.8 Ni 0.2 H 2.8 -B33″) and ordered migration mechanism of H atom (layered and linear de-/intercalation). Our attractive insights into the ultralong cycle life of ZrCo-based alloys through homogeneous structural phase transformation will serve as a pioneer on cycle optimization in the field of hydrogen storage materials. [Display omitted] • The as-cast alloy containing B33 phase was successfully prepared according co-substitution strategy. • Zr0.8Nb0.2Co0.8Ni0.2 shows the highest cycle capacity and retention among all reported alloys. • The splendid cycle stability comes from B33↔B33'' homogeneous structural phase transformation. • A novel H migration mechanism is proposed to replenish the classical site occupation theory. [ABSTRACT FROM AUTHOR]

To reduce the cost and modulate hydrogen storage performances of Ti-based Laves phase alloys for the application of inputting 3.2 MPa feed hydrogen and outputting 8 MPa hydrogen with water bath, three series of less-vanadium Ti–Zr–Mn–Cr–V based alloys were prepared by induction levitation melting, and their microstructure and hydrogen storage properties were systematically investigated. All alloys consist of a single C14-type Laves phase with well-distributed elements. With vanadium decreasing in Ti 0.95 Zr 0.05 Mn 0.9+ x Cr 0.9+ x V 0.2-2 x (x = 0–0.02) and Ti 0.93 Zr 0.07 Mn 1.1+ y Cr 0.7+ z V 0.2- y - z (y = 0, 0.05, z = 0–0.05) stoichiometric alloys, the hydrogen equilibrium pressure increases and hydrogenation kinetics is slightly deteriorated. After introducing Ti hyper-stoichiometry, Ti 0.93+ w Zr 0.07 Mn 1.15 Cr 0.7 V 0.15 (w = 0–0.04) alloys show decreased hydrogen equilibrium pressure, high hydrogen capacity and enhanced kinetics. Among alloys mentioned, Ti 0.95 Zr 0.07 Mn 1.15 Cr 0.7 V 0.15 has optimum performances including useable capacity of 1.07 wt% at working conditions, together with satisfactory cycling durability. This study guides for compositional design of high-density hydrogen storage multi-component alloys. [Display omitted] • Low-vanadium Ti–Zr–Mn–Cr–V based alloys were developed for high-hydrogen storage. • The kinetics is evidently improved by the introduction of Ti hyper-stoichiometry. • Ti 0·95 Zr 0·07 Mn 1·15 Cr 0·7 V 0.15 alloy has the best overall properties for application. [ABSTRACT FROM AUTHOR]

The microstructure and hydrogen storage properties of Ti 10+ x V 80- x Fe 6 Zr 4 (x = 0, 5, 10, 15) alloys have been studied. XRD and SEM analyses show that all alloys consist of a BCC main phase and a small fraction of C14 Laves secondary phase, in which the latter precipitates along the grain boundary of the former becoming network structure. With increasing Ti content in the alloy, the lattice parameter and cell volume of the BCC main phase of the alloy increase. The chemical composition of each phase is analysed by EDS, from which the lattice parameters of BCC phase have a good linear relationship with their average atomic radii. All bulk alloys have good activation behaviors and hydriding kinetics. With the increase of Ti content, the incubation time for activation decreases first and then increases under an initial hydrogen pressure of 4 MPa at 298 K. The incubation time of Ti 15 V 75 Fe 6 Zr 4 alloy is only 12 s. It is one of the shortest incubation time in V-based solid solution alloys as far as we know, which may be related to the existence of C14 Laves phase. All the alloys have relatively high hydrogen absorption capacities of above 3 wt%, which increase first and then decrease as the Ti content increases, achieving the maximum capacity of 3.61 wt% at x = 10 at 298 K. With increasing x , the equilibrium plateau pressure of dehydrogenation of the samples at 353 K decreases owing to the expansion of unit cell of main phase, which is far below 0.1 MPa for x = 10 and 15. The maximum desorption capacity of 1.94 wt% (desorbed to 0.001 MPa) is obtained at x = 5, compared to that of 1.6 wt% (desorbed to 0.1 MPa) achieved at x = 0. • Bulk Ti 10+ x V 80- x Fe 6 Zr 4 (x = 0, 5, 10, 15) are directly used into the activation. • The incubation time for activation for Ti 15 V 75 Fe 6 Zr 4 is only 12 s. • The substitution of Ti for V within 10 at.% enhances the absorption capacity. [ABSTRACT FROM AUTHOR]

Ti 0.85 Zr 0.17 Cr 1.2- x Fe 0.8 V x (x = 0–0.2), Ti 0.85 Zr 0.17 Cr 1.2- y Fe 0.7+ y V 0.1 (y = 0–0.25) and Ti 0.87- z Zr 0.15+ z Cr 0.95 Fe 0.95 V 0.1 (z = 0–0.04) alloys for metal hydride hydrogen compressor at moderate working temperatures were prepared by induction levitation melting. Their microstructures and hydrogen storage properties were systematically investigated. The results show that all Ti–Zr–Cr–Fe–V based alloys have a single C14 Laves phase structure. As the V content in the Ti 0.85 Zr 0.17 Cr 1.2- x Fe 0.8 V x (x = 0–0.2) alloys increases, better activation kinetics and larger hydrogen storage capacity are achieved, while the plateau pressure decreases and the plateau slope factor increases. Similarly, the hydrogen storage capacity, the plateau pressure and the plateau slope factor of the Ti 0.87- z Zr 0.15+ z Cr 0.95 Fe 0.95 V 0.1 (z = 0–0.04) alloys vary identically with Zr content increasing. Conversely, these three properties vary oppositely with increasing Fe content in the Ti 0.85 Zr 0.17 Cr 1.2- y Fe 0.7+ y V 0.1 (y = 0–0.25) alloys. Among the studied alloys, Ti 0.85 Zr 0.17 Cr 0.95 Fe 0.95 V 0.1 possesses the best overall properties for the designed moderate hydrogen compression application. [Display omitted] • Ti–Zr–Cr–Fe–V alloys are developed for hydride H 2 compressor at mild temperatures. • Effects of element partial substitution on the alloy properties are investigated. • Ti 0.85 Zr 0.17 Cr 0.95 Fe 0.95 V 0.1 possesses excellent properties for application. [ABSTRACT FROM AUTHOR]

In order to improve the activation behavior of Ti 1.02 Cr 1.1 Mn 0.3 Fe 0.6 alloy with high hydrogen desorption pressure for hybrid hydrogen storage vessel application, the rare earth (RE) doped Ti 1.02 Cr 1.1 Mn 0.3 Fe 0.6 RE 0.03 (RE = La, Ce, Ho) alloys were prepared by induction levitation melting. The effect of rare earth doping on the microstructures and hydrogen storage properties was also investigated systematically. The results show that Ti 1.02 Cr 1.1 Mn 0.3 Fe 0.6 alloy displays a single C14 Laves phase, and there is a secondary phase of rare earth oxide in the RE doped alloys. The RE doping strategy can expand the unit cell volume of C14 Laves main phase. After RE doping, the activation behavior of the Ti 1.02 Cr 1.1 Mn 0.3 Fe 0.6 RE 0.03 alloy is obviously improved and the hydrogen storage capacity is increased, while the hydrogen desorption plateau pressure is decreased. Moreover, the RE-free alloy can hardly absorb hydrogen at room temperature under 34–43 MPa hydrogen pressure, but all RE-doped alloys can absorb hydrogen to saturation under the same condition. The decline of pressure plateau is inversely proportional to the atomic number of RE. Among the studied alloys, the Ti 1.02 Cr 1.1 Mn 0.3 Fe 0.6 La 0.03 alloy shows the best overall properties and can be fully activated at room temperature. Its hydrogen absorption pressure is 39.31 MPa and 51.27 MPa under 298 K and 318 K, respectively. Its hydrogen storage capacity is up to 1.715 wt% and the dissociation enthalpy is 16.63 kJ/mol H 2 with a desorption plateau slope of 0.098. [ABSTRACT FROM AUTHOR]

AB 2 -type alloys have been widely used for metal hydride hydrogen compressors and hydrogen storage systems. The crystal structure and hydrogen storage properties mostly rely on their composition and atomic distribution. Thus, revealing the relationship between structure and properties can lead to the design of alloys with optimized properties for hydrogen storage application. Here, the structure stability, bonding energy, thermodynamic and kinetic properties of TiCr 2-x Mn x (x = 0, 0.25, 0.5, 0.75, 1) alloy/hydride have been firstly investigated by combining density functional theory calculation and experiment. It demonstrates that Mn-doped TiCr 2 alloy has a stable C14 phase, and Mn can optionally substitute for Cr sites. Additionally, with increase of Mn content, the desorption plateau increases and the ΔH value decreases. In particular, the ΔH values of TiCr 2-x Mn x hydrides are consistent with the heat released when H atoms occupy the interstitial interstices. Finally, the hydrogen absorption kinetics simulation shows that Mn is unfavorable to the hydrogen absorption kinetics, in which TiCrMn is 124 s longer than TiCr 2 when 90% hydrogen-absorption capacity is reached. The relationship between calculations and experiments presents here can be used as a reference for subsequent screening of alloying elements with high melting point and cost for metal hydride system. [Display omitted] [ABSTRACT FROM AUTHOR]

• Ti-Cr based alloys are investigated for H 2 compressor at water-bath temperatures. • Effects of element partial substitution on the alloy properties are studied. • Ti 0.88 Zr 0.14 Cr 0.9 Mn 0.2 Fe 0.8 V 0.1 has great comprehensive properties for application. Moderate operating temperatures and inert heat transfer medium are necessary for improving the safety of thermal hydrogen compression applications. In this work, the structural characteristics and hydrogen storage properties of Ti 0.85 Zr 0.17 Cr 1.7- x Mn 0.2 Fe x V 0.1 (x = 0.7, 0.8, 0.9) and Ti 0.82+ y Zr 0.20- y Cr 0.9 Mn 0.2 Fe 0.8 V 0.1 (y = 0, 0.03, 0.06) alloys for hydrogen compression under moderate thermal conditions of water bath were systematically investigated. The results show that all the alloys have a single C14 Laves phase. With increasing the Fe content in Ti 0.85 Zr 0.17 Cr 1.7- x Mn 0.2 Fe x V 0.1 (x = 0.7–0.9) or Ti content in Ti 0.82+ y Zr 0.20- y Cr 0.9 Mn 0.2 Fe 0.8 V 0.1 (y = 0–0.06) alloys, the hydrogen plateau pressure is obviously raised, however, the hydrogen storage capacity declines slightly. Flattened hydrogen plateau is also achieved when the Ti content increases. Therein, Ti 0.88 Zr 0.14 Cr 0.9 Mn 0.2 Fe 0.8 V 0.1 alloy, with achievement of hydrogen compression from 6.13 MPa at 293 K up to 23.73 MPa at 353 K and hydrogen capacity of 1.64 wt%, outperforms the others for the proposed thermal hydrogen compressor. [ABSTRACT FROM AUTHOR]

• Ti-Zr-Mn-Cr-V alloys were developed for high-density hydrogen storage. • Performances under mild condition are improved by element partial substitution. • Ti 0.95 Zr 0.05 Mn 0.9 Cr 0.9 V 0.2 exhibits comprehensive properties on hydrogen storage. [Display omitted] Two series of Ti 1- x Zr x Mn 1.1 Cr 0.7 V 0.2 (x = 0.05, 0.06, 0.07, 0.1) and Ti 0.95 Zr 0.05 Mn 1.8- y Cr y V 0.2 (y = 0.5, 0.7, 0.9) alloys were developed for high-density hydrogen storage units. The effect of partial substitution of Zr for Ti and Cr for Mn on microstructures as well as hydrogen storage performances was systematically investigated. All prepared alloys are determined as a single phase of C14-type Laves structure and uniform element distribution. As Ti is increasingly substituted with Zr in the Ti 1- x Zr x Mn 1.1 Cr 0.7 V 0.2 (x = 0.05–0.1) alloys, the hydrogen storage capacity increases gradually, while the plateau pressures decrease drastically. For Ti 0.95 Zr 0.05 Mn 1.8- y Cr y V 0.2 (y = 0.5–0.9) alloys, with the increase substitution of Cr for Mn, equilibrium pressure hysteresis of de-/hydrogenation improves significantly, while the plateau pressures and the hydrogen storage capacity decrease slightly. Among the studied alloys, Ti 0.95 Zr 0.05 Mn 0.9 Cr 0.9 V 0.2 is the most suitable for high-density hydrogen storage units with excellent cycling performances. The hydrogen storage capacity is 1.78 wt% in gravimetry and 118.33 kg/m3 in volumetry. The desorption plateau pressure at 90 ℃ is 9.37 MPa with extremely low hysteresis, and dissociation enthalpy is − 21.64 kJ mol−1. This work provides a guideline for the alloy composition design of Ti-based alloys. [ABSTRACT FROM AUTHOR]

In order to optimize the hydrogen isotope storage properties of ZrCo alloy and promote its application in the storage and delivery system (SDS), ZrCo alloy is modified by partial substitution of Co with Al and subsequent melt spinning process. The microstructure and hydrogen isotope storage properties, especially the cycling performance, of ZrCo 1- x Al x (x = 0–0.15) samples were thoroughly investigated. It is found that all as-cast Al-substituted alloys are consisted of a main phase of ZrCo, while the segregation of Al element at grain boundary is more serious with the increase of Al doping content, which restrains the valid substitution content of Al for Co in ZrCo phase. The initial activation performances of the Al-substituted alloys are enhanced and excellent hydriding kinetics are maintained. With the increase of Al substitution content in ZrCo phase of ZrCo 1- x Al x (x = 0–0.15) alloys, the initial saturated hydrogen capacities of α solid-solution phase are improved significantly, which is attributed to the decline of valence electron concentrations (VEC) for Al-substituted alloys. Further analysis shows that the hydrogenation-dehydrogenation process of ZrCo 1- x Al x (x = 0–0.15) alloys after multiple cycles has been altered as intercalation and de-intercalation of hydrogen atoms between ZrCo phase and α phase, leading to cycling capacity stabilization. More importantly, the improved terminal saturated hydrogen capacities of α phase in the Al-substituted alloys, which represents enhanced final cycling stable capacities, is linked with the increase of initial saturated hydrogen capacities of α phase after Al substitution for Co in ZrCo phase. In addition, the valid substitution content of Al for Co in ZrCo phase is further increased without any element segregation for ZrCo 0.9 Al 0.1 alloy processed by melt spinning, which behaves further optimized final cycling stable capacity of 0.93 wt%, and its variation of the hydrogenation and dehydrogenation paths is similar to those of the above samples. In this work, the mechanism of cycling capacity stabilization has been explored in detail, which provides guidance to improve the cycling stability of ZrCo-based hydrogen isotope storage alloys from point of phase structure of ZrCo alloy. • The hydrogen capacity of α phase for ZrCo 1-x Al x is improved by Al substitution. • De-/hydriding behaviors of ZrCo 1-x Al x are altered after multiple cycles. • Enhancing hydrogen capacities of α phase can improve the stability of Zr–Co–Al. [ABSTRACT FROM AUTHOR]

[Display omitted] • A combined experimental and numerical study of hydrogen compression bed is performed. • A theoretical framework is summarized for model construction and verification. • Two tanks filled with 20 g and 700 g alloy are designed to confirm the simulation. • The section view of temperature distribution for de-/hydrogenation can be predicted. A slow kinetic rate caused by the strong exothermic/endothermic effect is the main bottleneck restricting the practical application of metal hydride tanks for hydrogen compression. Numerical simulation is a powerful way to optimize the thermal management of the system, as long as a quantitative model can be obtained for accurate predictions of de-/hydrogenation performance. Here, we focus on a combined experimental and numerical study of the specific Ti 0.92 Zr 0.10 Cr 1.0 Mn 0.6 Fe 0.4 hydride beds. The kinetic and thermodynamic parameters for the hydrogen absorption and desorption required by the simulation model are first determined, accompanied by an excellent coincidence between measured and fitted results. Meanwhile, two cylindrical test tanks of different sizes were designed to illustrate the hydrogenation and dehydrogenation properties of the metal hydride bed in different scenarios, with 20 g of powder in the small reactor and 700 g in the large one. Further results reveal that the temperature evolution curves obtained from experiments can be well matched with simulation, proving the dependability of the self-designed numerical model and favoring the subsequent performance optimization of the metal hydride tanks. This investigation is of general value for the numerical simulation of advanced hydrogen storage applications. [ABSTRACT FROM AUTHOR]

Abstract: Effects of Bi2O3 addition and ball-milling time on the electrochemical performance of the ball-milled La2Mg17 +200wt.% Ni composites in 6M KOH aqueous solution were investigated. The electrode characteristics of mechanically ground composites of La2Mg17 +200wt.% Ni with and without 1wt.% Bi2O3 were examined such as discharge capacity, high-rate dischargeability and cycle life. It is demonstrated that for the original ball-milled composites, the high-rate dischargeability and cycling stability improved with the increase of ball-milling time, but the discharge capacity was just on the contrary. However, when the composites ball-milled with 1wt.% Bi2O3 for different times, the effect on the discharge capacity, high-rate dischargeability and cycling stability can be very different depending on the mechanical grinding time. [Copyright &y& Elsevier]

Abstract: The effects of mechanical ball-milling on the hydriding/dehydriding behaviors of La1.8Ca0.2Mg14Ni3 alloy were investigated. The time of ball-milling under an argon atmosphere is 10, 15 and 20h, respectively. The changes in phase structure and morphology of the samples were analyzed through XRD and scanning electron microscope (SEM). The results show that mechanical ball-milling can improve the hydrogen absorption/desorption kinetics of La1.8Ca0.2Mg14Ni3 alloy. The milled alloys of La1.8Ca0.2Mg14Ni3 show much better hydriding/dehydriding behaviors than the as-cast alloy. Among the alloys studied, the alloy milled for 20h shows the best overall property. [Copyright &y& Elsevier]