Alloy Powders Research Articles

Enhanced Combustion Properties of Al-Si Eutectic Alloy in Energetic Mixtures

This study investigates the feasibility of using an Al-Si eutectic alloy as a reactive fuel in energetic mixtures. Al-Si eutectic alloy powders were obtained from secondary resources and ground to a particle size of less than 100 μm. We examined these powders’ burning characteristics and thermal properties compared to pure Al powder. Results showed that the burning rate of energetic mixtures containing Al-Si eutectic alloys was 1.5 to 2.0 mm/s higher than those with pure Al. Additionally, the activation energy of pure PTFE was reduced from 81.29 kJ/mol to 61.75 kJ/mol when the Al-Si alloy was added. The formation of oxides, carbides, and fluorides in the combustion products of Al-Si-based mixtures significantly influenced their thermodynamics.

Optimum Oxygen Concentration in Powder Bed Fusion Using Laser Beam for Building of Sc-containing Aluminum Alloy Powder.

Optimum Oxygen Concentration in Powder Bed Fusion Using Laser Beam for Building of Sc-containing Aluminum Alloy Powder.

Microstructures and properties of a novel cemented carbide prepared using a Co–Ni–Cu multiprincipal element alloy as the binder

A Co–Ni–Cu multiprincipal element alloy (MPEA) powder was successfully synthesized through coprecipitation. Results of energy dispersive spectroscopy (EDS) and X-ray fluorescence spectroscopy (XRF) revealed nearly equal atomic ratios for Co, Ni, and Cu in the Co–Ni–Cu MPEA powder. Moreover, X-ray diffraction (XRD) confirmed a single-phase face-centered cubic (fcc) structure in the Co–Ni–Cu MPEA powder. To explore the differences in microstructure and mechanical properties, we compared a novel WC–2Co–2Ni–2Cu cemented carbide, utilizing the Co–Ni–Cu MPEA as a binder, with conventional WC–6Co and WC–3Co–3Ni cemented carbides prepared via liquid phase sintering. This comparison was conducted using scanning electron microscopy, XRD, and mechanical properties testing. Observations revealed that the surfaces of WC grains in WC–2Co–2Ni–2Cu and WC–6Co appeared smooth and flat, while those in WC–3Co–3Ni exhibited roughness with numerous terraces. In addition, the average grain size was 0.96, 1.14, and 1.22 μm in WC–2Co–2Ni–2Cu, WC–6Co, and WC–3Co–3Ni, respectively. Notably, the Co–Ni–Cu MPEA inhibited WC grain growth. WC–2Co–2Ni–2Cu (1388 HV30) exhibited hardness similar to that of WC–6Co (1406 HV30) but the highest fracture toughness (9.04 MPa∙m1/2), while WC–3Co–3Ni (1332 HV30) presented the lowest hardness. Bending strength values were recorded at 2406 MPa for WC–2Co–2Ni–2Cu, 2816 MPa for WC–6Co, and 2645 MPa for WC–3Co–3Ni, with WC–6Co exhibiting the highest bending strength. Considering their microstructures, physical properties, and mechanical properties comprehensively, the novel cemented carbides exhibited only slightly reduced bending strength compared to conventional counterparts. Thus, the Co–Ni–Cu MPEA binder demonstrates promising potential as a replacement for the conventional Co metal binder.

Experimental and simulation studies to optimize the mechanical alloying process of ODS-FeCrAl alloy powder

Oxide dispersion strengthened (ODS) FeCrAl alloy exhibits superior mechanical qualities at high temperatures and resistance to neutron irradiation, making it a highly promising material for accident-tolerant fuel cladding. The preparation of ODS-FeCrAl alloy powder by mechanical alloying can mix Y2O3 and FeCrAl alloy powder uniformly and promote the uniform dispersion of nanoscale oxide particles in the alloy matrix. The preparation of ODS-FeCrAl alloy powder by the mechanical alloying method is greatly influenced by the rotational speed. Therefore, this study uses a combination of experiments and numerical simulation to investigate the effects of different rotational speeds on the microscopic morphology, particle size and force of alloy powder during the ball milling process. The mechanically alloyed powder was subjected to XRD inspection to determine the optimum ball milling time at each rotational speed by means of the maximum lattice distortion, and then the powder micromorphology and particle size were analyzed. Then the forces on the powder and grinding ball during the ball milling process were analyzed by numerical simulation, and it was found that the collision force and normal force played a dominant role in the ball milling process. The combined experimental and simulation results determined that the ODS-FeCrAl alloy powder obtained by ball milling at 300 rpm for 35 h had the largest lattice distortion, fine grain size and uniform particle size, which achieved the best mechanical alloying effect.

Microstructure and magnetic properties of surfactant-assisted ball milling NdFe8Co2Mo2 powders and their nitrides

The NdFe8Co2Mo2 alloy ribbons were prepared by melt-spinning. The powder was prepared through surfactant-assisted ball milling, followed by nitriding to produce the NdFe8Co2Mo2Nx alloy. The alloy ribbons grain size decreases as the copper roller speed increases. At the speed of 30 m/s, a pure 1:12 phase alloy ribbons were produced. The grain size decreases with increasing the ball milling time, but the composition phases almost unchanged of the alloy powder. The grain size refine after nitriding, but the grain volume expands when the nitriding temperature exceeds 500 °C. With increasing ball milling time and nitriding temperature, the remanence (Mr) and coercivity (Hc) of the alloy powder increase first and then decrease. The alloy powder obtained from ball milling for 3 h after nitriding at 475 ℃ for 3 h, resulting in Mr was 44.43 Am2/kg, Hc was 0.434 T, and saturation magnetization (Ms) was 74.89 Am2/kg.

Cu-Al-Ni Nanocrystalline Compacts Obtained by Spark Plasma Sintering of Mechanically Alloyed Powders.

The aim of this work is to obtain Cu-13.5Al-4Ni alloy for use as shape memory alloy by Spark Plasma Sintering (SPS) of mechanically alloyed powder. The study investigates the structural and microstructural changes in terms of crystal parameters, crystallite sizes, and phases evolution during mechanical alloying and spark plasma sintering of Cu-13.5Al-4Ni powders. We obtained alloyed powders with a structure composed of α(Cu), AlNi intermetallic compound and small amounts of elemental Al through the mechanical alloying technique. After spark plasma sintering at 900 °C, the microstructure consists of an AlNi compound distributed at the edge of α(Cu) grains. The crystallite sizes of both, α(Cu) and AlNi are in nanoscale order after 16 h of milling (9 and 6.5 nm respectively). After sintering at 900 °C (in Ar atmosphere, without holding time), the crystallite sizes increase to 46 nm for α(Cu) and to 40 nm for AlNi compound. Also, the Cu-13.5Al-4Ni compacts achieve a final density after sintering at 900 °C of around 80% from the theoretical density.

Wear behavior of CoCrFeNi high-entropy alloy prepared by mechanical alloying

Equiatomic quaternary CoCrFeNi powder was prepared from the individual metals by mechanical alloying of the mixed powders at room temperature. The as-milled powder contained particles of irregular shape with an average particle size of 0.62 μm, and exhibited a dual-phase composition of the face-centered cubic and the body-centered cubic structures. The as-milled powder was consolidated by hydraulic pressing at room temperature and sintered at 950 °C in argon and vacuum. The compacted material exhibited a single-phase composition of the face-centered cubic structure alone and a chemical composition close to equiatomic with uniform distribution of all constituents, indicating that the desired CoCrFeNi high-entropy alloy (HEA) had been formed. The microhardness of the vacuum-sintered CoCrFeNi HEA was measured to be 118±7 HV, exceeding that calculated by the rule of mixture. The coefficient of friction was determined by pin-on-disk dry sliding studies at room temperature and found to be 0.65 and 0.44 for the applied loads of 25 for 35N, respectively, and the corresponding wear rates were 4.6×10-4 and 9.1×10-4 mm3/N·m. XPS studies on the worn alloy surfaces showed the formation of oxidized tribo-layers, composed of predominantly Cr2O3. Overall, this study has demonstrated that mechanical alloying followed by simple furnace sintering at a moderate temperature is able to yield an abrasion-resistant CoCrFeNi HEA suitable for structural applications.

Preparation process, surface properties and mechanistic study of HVAF-sprayed CoCrFeNiMo0.2 high-entropy alloy coatings

The objective of this study is to develop infrared reflective coatings with excellent service performance in extreme environments, aimed at reducing system energy consumption and enhancing service life. In this work, CoCrFeNiMo0.2 high-entropy alloy (HEA) powder was deposited on the 316 L stainless steel (SS) substrate using High-Velocity Air Fuel (HVAF) thermal spray technology. The microstructure, mechanical properties, infrared reflectivity, and corrosion resistance of the coatings under different spraying parameters were investigated and compared with those of the substrate. Computational Fluid Dynamics (CFD) simulation was employed to analyze the influence of HVAF spraying parameters on flame characteristics and particle flight behavior, providing guidance for optimizing the spraying process and explaining underlying mechanisms. Results demonstrated that adjusting parameters such as propane and air pressure, spraying distance, and powder feed rate could produce dense coatings with <1 % porosity. The microhardness of the coatings was approximately 1.8 times that of the substrate, and the bonding strength between the coating and the substrate is increased to 39.4 MPa. Additionally, the near-infrared reflectivity of the coatings was significantly higher than that of the substrate, with an enhancement of 18.7 %. Coatings sprayed under different parameters exhibited superior passivation and pitting corrosion resistance compared to the substrate in 3.5 wt% NaCl and 1 mol/L HCl solutions. Optimization of spraying parameters further enhanced the protective capability of the passivation film and corrosion resistance. Consequently, CoCrFeNiMo0.2 HEA coatings prepared by HVAF spraying technology demonstrate excellent comprehensive performance, holding promising potential for industrial applications.

Synthesis, Microstructural Investigation, and Mechanical Behavior of AA5083/Boron Nitride Nanocomposite

The as‐received aluminum alloy (AA5083) powders (44 μm) and hexagonal boron nitride (BN) nanoparticles (65–75 nm) are used to fabricate AA5083‐BN nanocomposites with varying BN content (0, 3, 6, 9, and 12 wt%). A powder metallurgy solid‐state method is employed, involving ball milling for 20 h at 100 rpm with a ball‐to‐powder mass ratio of 10:1. The processed powders are then consolidated through forging–sintering at 550 °C for 30 min, followed by hot forging at 225 MPa. The microstructure is examined using X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray, transmission electron microscopy, and electron backscatter diffraction to understand the effect of processing variables. The compaction behavior is investigated both experimentally and empirically, revealing a relative green density exceeding 88% at 500 MPa. The empirical models display coefficients of determination (R2 values) exceeding 99% for predicting the compaction behavior. Compression tests on bulk samples show that BN reinforcement significantly enhances ultimate compressive strength, with values reaching 473.256 ± 5.54, 536.374 ± 2.87, 567.694 ± 4.22, and 601.911 ± 6.54 MPa for TRB‐3, TRB‐6, TRB‐9, and TRB‐12, respectively. The developed composites achieve relative densities greater than 97%, indicating promising applications in the aerospace, automotive, and marine industries.

The influence of anisotropy on the character of hardening in additive high-strength alloys

The purpose of this work is to establish the dependence of the coefficients of planar anisotropy on the intensity of localized deformations in various loading ranges of transverse and longitudinal sections of samples of heat-resistant powder alloy Inconel 718 manufactured using SLM technology. The role of technological anisotropy of samples characteristic of SLM technology and its effect on the hardening of Inconel 718 alloy products is evaluated. Methods. To achieve this goal, the deformation diagrams of Inconel 718 powder alloy samples manufactured using SLM technology, measured during their stretching according to GOST 11701-84, were analyzed. Flat samples with a dividing grid applied to their surface were subjected to loading. During the tests, localized deformation of the samples in different sections was determined by measuring the geometry of the images of the dividing grid. A specially developed photo and video recording technology was used to capture these images. Results. The statistical analysis of the type and parameters of the deformation diagrams made it possible to determine the nature of changes in the intensity of stresses and deformations of the samples of the studied material. The linear character of its tensile hardening in the region of small values of strain intensity and the power-law character of hardening in the range of strain intensity from 0.03 to 0.17 were established. Conclusion. A significant effect of the technological anisotropy of Inconel 718 heat-resistant powder alloy samples obtained using SLM technology on the intensity of deformations is shown. The necessity of taking this fact into account in the development of technological processes for the production of responsible products from the studied material has been revealed.

Структура та властивості багатошарового металу, наплавленого електродними порошковими дротами з осердям із порошків феросплавів та гранульованих твердосплавних матеріалів

Comparative studies of the possibility of using granulated hard alloy powders as a charge of flux-cored wires for electric arc surfacing have been carried out. In the studies, granulated powder of the PG-R6M5 brand with a fraction of 50...300 μm was used. As a standard, a flux-cored wire was used, in the core of which there was a composition of powders of different ferroalloys of the same fraction. The content of the charge components in the core of the standard wire was selected and calculated so as to obtain a similar chemical composition to the wire containing granulated hard alloy powder. The test samples were obtained by layer-by-layer electric arc surfacing under the flux layer with flux-cored wires on low-carbon steel plates. To obtain identical dependences, the flux-cored wires had the same diameter and filling factor and differed only in the content of the core. The test samples were deposited under the same conditions with strict adherence to the deposition regimes, which were monitored using a high-speed analog-to-digital converter. It was determined that the use of granulated hard alloy powder as a charge of flux-cored wire has a positive effect on the melting characteristics of the wire and the stability of the welding process in general in comparison with the standard reference wire, the charge of which contains ferroalloys. This effect can be explained by the greater chemical purity of the granulated powder and the uniformity of the physicochemical properties of its particles in comparison with the powders of various ferroalloys. The determined features of the melting of the wire with a charge with granulated hard alloy powder have a positive effect on the quality of the formation of the multilayer deposited metal and its structure, leading to an increase in its homogeneity, some grinding of the grain and a decrease in the number and size of microdefects, which should positively affect the operational properties of the deposited metal. Keywords: electric arc surfacing, multilayer deposited metal, tool steels, granular hard alloy powder, ferroalloy, metal structure.

Ti6Al4V alloy with diamond particle-reinforced Cu-based coatings: Microstructure and tribological performance

To enhance the surface wear resistance of the Ti6Al4V alloy, diamond particles-reinforced Cu-based composite coatings (D500/D1000/D2000 coating: 500/1000/2000 mesh diamond: Cu-based alloy powder = 1:30 (wt%)) were fabricated by vacuum cladding. Cu-based alloys with liquid phase temperatures lower than the phase transition temperature of Ti6Al4V alloys were employed as cladding materials to avoid performance deterioration of Ti6Al4V substrates. The microstructure, mechanical properties, and dry-sliding tribological properties of the Cu-based composite coatings have been investigated systematically. The Cu-based composite coatings are composed of the ductile intermetallic compounds Ti3Sn and SnTi2 as the metal matrix, the hard and brittle intermetallic compounds CuTi, CuTi2, Ti(Cu, Al)2 and CuSn3Ti5, in situ generated TiC and the directly introduced diamond particle as the reinforced phases. In addition, a TiC hard phase protective layer was formed around the diamond particles, which retained the original properties of the diamond. The hardness of diamond particles-reinforced Cu-based composite coatings is much higher than that of the Ti6Al4V. Among them, the D2000 coating possesses the highest microhardness. The average Vickers hardness (HV0.5) on the coating surface and nanoindentation hardness (H) on the coating cross-section (the middle part without diamond particles) of the D2000 coating are 1329.8 HV0.5 and 16.87 GPa), which are 4–5 times higher than that of the Ti6Al4V substrate (333 HV0.5 and 3.37 GPa). Nevertheless, the D2000 coating (wear rate of 50.75 ×10−5 mm3/Nm) demonstrates slightly inferior tribological performance compared to the D500 coating. The wear rate of the latter is approximately 13.37 × 10−5 mm3/Nm, which is only 1/5.6 of the substrate (75.67 ×10−5 mm3/Nm). The larger the diamond particle size, the more the diamond serves as a bearing capacity support point to prevent the hard WC ball from further ploughing into the composite coating, and the better the wear resistance of the coating. Notably, D500 coating with excellent wear resistance has the potential for application in various fields of the machinery industry, marine engineering, and aerospace.

Simulation and Experimental Investigation of Fe-based Alloy Powder Production by Gas Atomization

Simulation and Experimental Investigation of Fe-based Alloy Powder Production by Gas Atomization

Laser energy-dependent processability of non-equiatomic TiNbMoTaW high-entropy alloy through in-situ alloying of elemental feedstock powders by laser powder bed fusion

Pre-alloyed powder, which is primarily used in laser powder bed fusion (LPBF), has the disadvantages of requiring time and high manufacturing costs. To overcome these limitations, in-situ alloying, which mixes pure elemental powders and alloys them in real-time during the LPBF process, has attracted attention. In particular, manufacturing high entropy alloys (HEA) containing high-melting-point refractory elements through in-situ alloying presents considerable challenges. In this study, a non-equiatomic single body-centered cubic (BCC) solid-solution HEA was fabricated via in-situ alloying with Ti, Nb, Mo, Ta, and W powders through the LPBF process. Specifically, by applying a high volumetric energy density (VED), we successfully mitigated the segregation of constituent elements, leading to an enhanced crystallographic texture. Consequently, the reduction in the residual stress and high-angle grain boundary (HAGB) density progressed, contributing to an increased relative density. Thus, this study marks a pioneering endeavor for in-situ alloyed HEA fabrication via LPBF, illustrating the efficacy of in-situ alloying utilizing mixed powders.

Microstructure and tribological performance of novel Ni-based alloy cladding with excellent high temperature wear resistance and self-lubrication performance

This paper aims to study the laser cladding of Ni-based alloy coatings with excellent high temperature wear resistance and self-lubrication performance on the surface of parts such that meet complex metallurgical service conditions. The composite alloy powders were formed by adding 3 wt%–11 wt% WS2 and Ti powder to NiCrCoMoBSi alloy powder, and the novel Ni-based alloy samples with high temperature wear resistance and self-lubrication performance were cladded on the surface of Cr28Ni48W5 substrate by laser cladding. The results show that the addition of WS2 and Ti powder had a significant influence on the microstructure evolution and high temperature wear resistance and self-lubrication performance of the samples. The laser cladding coating with 7 wt% WS2 and Ti had the 3 % TiS self-lubricating phase and 19 % enhanced phase with the best microstructure matching relationship, which improved the high temperature wear resistance and self-lubrication performance of the sample. At 800 °C, compared with the Cr28Ni48W5 superalloy substrate, the friction coefficient of the laser cladding coating was 0.22 and the wear ratio was 1.70 × 10−5 mm3 N−1 m−1, which were reduced by 60 % and 54.67 % respectively. The mechanism of the enhanced wear resistance and self-lubrication performance was elaborated.

Heterogeneous amorphous/crystalline ZnZrCu biodegradable alloys with synergistic strength–plasticity prepared by mechanical alloying and laser powder bed fusion

ABSTRACT Amorphous Zn-based alloys have shown considerable potential for implant applications owing to the impressive strength. However, they inevitably fall into strength–plasticity trade-off dilemma due to shear bands softening. In this work, a novel and feasible route of mechanical alloying (MA) and laser powder bed fusion (LPBF) was first developed for manufacturing heterostructured ZnZrCu alloys. The results showed that MA destabilised atomic periodicity of Zn/Zr powders and induced amorphization. Furthermore, increasing Cu content enhanced amorphization ability and in-situ synthesised ϵ-phases, endowing ZnZrCu powders with heterostructure. During LPBF, the fast-melting kinetics and highly localised nature restricted devitrification and promoted the uniform distribution of ϵ-phases, constructing heterogeneous amorphous/crystalline ZnZrCu alloys. Consequently, ZnZrCu alloys exhibited good strength–plasticity synergy attributed to extra strain-hardening and hampering premature failure of shear bands. This study not only provides a feasible route to prepare biodegradable Zn-based alloys with strength–plasticity synergy but also sheds light on the design and manufacture of cutting-edge amorphous alloys.

Optimizing Cold Spray Parameters for High Entropy Alloy Coatings Using Taguchi and Box–Behnken Design Approaches for Mechanically Alloyed Powder

AbstractThe present study focused on optimizing the cold spray (CS) process parameters for depositing Fe20Cr20Mn20Ni20Co20 (Cantor alloy) coatings using mechanically alloyed (MA) powder. A two-step design of experiments approach was employed, beginning with the initial screening of input variables using the L8 Taguchi method, followed by the refinement of process parameters through the Box–Behnken design of experiments. Key performance indicators included deposition efficiency (DE), coating thickness per pass, and microstructural parameters including porosity, cracks, and interfacial defects/delamination. The study identified process gas temperature as the primary factor influencing both DE and thickness per pass. Higher gas temperature and pressure, combined with increased scanning speed, resulted in higher DE. The DE of the MA Cantor alloy powder peaked at around 14-15%, with a deposit density greater than 99% achieved at the highest process gas temperature and pressure (1000 °C and 60 bar, respectively). The average hardness of the optimal CS coating deposited using MA powder was found to be 679 ± 17 HV0.1, which is approximately 90% greater than the average hardness reported for CS coatings deposited using atomized powder.

Integrated framework of multi−physics mechanism models for gas−powder flow, molten pool evolution and part deformation in high alloy steel additive manufacturing process

Multi−physics numerical models for metal additive manufacturing (MAM) could replace the expensive trial−and−error experiments, reveal the mechanisms of printing process, and provide an effective means of optimizing process parameters and mitigating part defects. However, the existing simulations of MAM process seldom consider the coupling effects between multiple recursive processes. There is an urgent need to overcome the dilemma of limiting MAM process simulation to a localized single sub−process. For directed energy deposition (DED) additive manufacturing process, the integrated simulation framework proposed in this study consists of a gas−powder flow model, a heat and fluid flow model, and a sequentially coupled thermal–mechanical model, which can be used to predict the feedstock feeding process, the evolution of molten pool, and the residual deformations of metal part, respectively. The accurate results of the three recursive sub−processes can be obtained by delivering the validated parameters between models. Corresponding experiments are conducted to verify the accuracy of the integrated framework based on 12CrNi2 alloy powders. The deviation of the predicted focal distance of powder streams is 5.14 %, and the deviations of the predicted molten pool height and width are all less than 8.5 %. The integrated framework could rapidly and accurately predict the residual deformation tendency and the position where the maximum deformation occurs. For single−track and eight−layer line deposition, the deviations of the predicted maximum deformation are all within 0.1 mm. The integrated framework could efficiently provide accurate and comprehensive solutions for optimizing DED process.

Microstructural evolution and interfaces in cold sprayed hybrid aluminum alloy powders of different hardness

The development of thick cold sprayed deposits of hard amorphous/nanocrystalline Aluminum High Entropy Alloys (Al HEA) is limited by their poor plastic deformability. To address this, Al HEA powder (Al90.05Ni4.3Y4.4Co0.9Sc0.35 (at. %)) is blended with soft Al 6061 in a 1:1 wt% ratio and cold sprayed. The microstructure of the composite deposits reveals that while Al HEA splats undergo limited deformation, Al 6061 splats deform extensively. Extreme deformation of Al 6061 captures the hard Al HEA particles, resulting in a composite deposit of 5 mm thickness, compared to 0.2 mm for pure Al HEA. Within the composite, Al HEA particles deform through shear band propagation and viscous flow, whereas Al 6061 splats deform via dislocation slip motion. These deformation mechanisms induce interface nanocrystallization, leading to a 123 % increase in lattice strain, a 67 % reduction in crystallite size, and an 800 % increase in dislocation density compared to the initial feedstock. This microstructural evolution, combined with the presence of hard Al HEA regions, results in a mean hardness of 2.56 GPa and an elastic modulus of 76 GPa. These values represent a 47 % and 6 % improvement over conventional polycrystalline cold-sprayed aluminum deposits. Thus, this study provides insights into the microstructural and interface evolution and its effect on indentation characteristics for making high-strength Al HEA deposits.

Investigating the Effects of Transition Metals and Activated Carbon on Hydrogenation Characteristics of Severely Deformed ZK60 Processed by High-Energy Ball Milling.

The synergic effects of activated carbon and transition metals on the hydrogenation characteristics of commercial ZK60 magnesium alloy were investigated. Severe plastic deformation was performed using equal-channel angular pressing with an internal die angle of 120° and preheating at 300 °C. The ZK60 alloy samples were processed for 12 passes using route BA. The deformed ZK60 alloy powder was blended with activated carbon and different concentrations of transition metals (Ag, Pd, Co, Ti, V, Ti) using high-energy ball milling for 20 h at a speed of 1725 rpm. The amount of hydrogen absorbed and its kinetics were calculated using Sievert's apparatus at the higher number of cycles at a 300 °C ab/desorption temperature. The microstructure of the powder was analyzed using an X-ray diffractometer and scanning electron microscope. The results indicated that 5 wt% activated carbon presented the maximum hydrogen absorption capacity of 6.2 wt%. The optimal hydrogen absorption capacities were 7.1 wt%, 6.8 wt%, 6.7 wt%, 6.64 wt%, 6.65 wt%, and 7.06 wt% for 0.5 Ag, 0.3 Co, 0.1 Al, 0.5 Pd, 2 Ti, and 0.5 V, respectively. The hydrogen absorption capacities were reduced by 35.21%, 26.47%, 41.79%, 21.68%, 26.31%, and 26.34% after 100 cycles for 5C0.5Ag, 5C0.3Co, 5C0.1Al, 5C0.5Pd, 2Ti, and 5C0.5V, respectively. Hydrogen absorption kinetics were significantly improved so that more than 90% of hydrogen was absorbed within five minutes.