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H 2 generation through hydrolysis of Al-composites has received eclectic attention for on-demand H 2 applications such as low-power proton exchange membrane fuel cells. In this line, we prepared Multi-Walled Carbon Nanotubes (MWCNT)/Al–Bi–NaCl nanocomposites and tested them for enhanced H 2 generation. These nanocomposites are prepared using high-energy ball milling followed by uni-axial cold compaction. H 2 generation by these nanocomposites was tested using tap water at room temperature. An excellent maximum H 2 generation rate of 13.33 mLg−1s−1 with an H 2 yield of 98% and an induction time of less than 10 s is achieved. Analysis of different observations shows that adding an optimum percentage of MWCNT to the Al–Bi–NaCl composite results in flaky morphology, which facilitates easily accessible water pathways, enhancing the H 2 generation rate of the nanocomposites. Also, an enhanced number of MWCNT/Al–Bi microgalvanic cells, optimum utilization of electrical conductivity of MWCNT, and dissolution of NaCl favored the H 2 generation. [Display omitted] • MWCNT/Al–5Bi–5NaCl nanocomposites are prepared by milling and cold compaction. • H 2 yield of 98% and an induction time of <10 s is achieved. • Maximum H 2 generation rate of 13.33 mLg−1s−1 is achieved. • The synergistic effect of MWCNT and NaCl enhanced H 2 generation. • An optimum quantity of MWCNT is required for the best results. [ABSTRACT FROM AUTHOR]

Metallic substances are favored for storing and transporting spent nuclear fuels (SNFs) due to their thermal stability, mechanical strength, and corrosion resistance. Adding gadolinium (Gd) significantly enhances neutron shielding, improving efficiency with reduced thickness and dimensions. In this study, Al–Gd 2 O 3 metal nanocomposites were synthesized using powder-processed mechanical milling. The crystal structure features of (100-x)Al-x%Gd 2 O 3 samples with varying percentages of Gd 2 O 3 (5 %, 10 %, and 15 % by weight) were analyzed by X-ray diffraction. Microstructural properties were studied using scanning and transmission electron microscopy (SEM and TEM). The synthesized composites' neutron and γ-radiation shielding characteristics were investigated theoretically using the MCNP6.2 transport code. Analysis of the XRD data revealed prominent peak shifts with increased milling time, indicating reduced particle sizes. Differential scanning calorimetry (DSC) indicated Gd 2 O 3 -induced changes in temperature behavior, and the Vickers microhardness tests demonstrated enhanced mechanical strength with increasing gadolinium concentration. Improved neutron radiation shielding was observed with higher Gd 2 O 3 content. Our study highlights the potential of Gd 2 O 3 -enriched metal matrix composites for advanced industrial applications. [ABSTRACT FROM AUTHOR]

This study investigates the impact of Sm3+ substitution on the structural, electrical, magnetic, and electrochemical properties of CoFe 2 O 4 nanoparticles prepared via a combined solid-state reaction and mechanical milling approach. Rietveld refinement analysis confirms the presence of single-phase cubic spinel structures within the Fd3m space group for both CoFe 2 O 4 (CF) and Co 0.95 Sm 0.05 Fe 2 O 4 (SmCF). Field emission scanning electron microscopy and energy dispersive spectroscopy are employed to validate the microstructure and elemental composition. Tauc plot analysis reveals a decrease in the band gap from 2.24 eV for CF to 2.07 eV for SmCF. Hysteresis loop measurements demonstrate an enhancement in saturation magnetization, remanent magnetization, and magnetic moment for SmCF, indicating improved magnetic properties. Furthermore, a substantial increase in magneto-crystalline anisotropy is observed with Sm³⁺ doping. Frequency-dependent dielectric properties are investigated using Havriliak–Negami fitting, confirming the presence of Cole-Cole dispersion. A direct correlation between the dielectric constant and temperature is identified, suggesting higher temperatures lead to elevated values. Notably, the incorporation of Sm³⁺ results in a significant enhancement in specific capacitance, positioning SmCF as a promising candidate for energy storage applications, particularly in supercapacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Emulsion-assisted milling used to develop new boron-based fuels. • Boron and PTFE are combined into spherical composite powders. • New fuels have a reduced ignition temperature. • New fuel produces greater pressure than neat boron. • Spherical fuels have enhanced flowability compared to commercial boron. This work is aimed to develop improved boron-based fuels capable of taking the full advantage of its high theoretical volumetric and gravimetric heats of combustion. Emulsion-assisted milling (EAM) was used to prepare spherical composite powders combining boron with 1 – 10 % polytetrafluoroethylene (PTFE) with particle sizes close to 10 µm. Different characteristics of the prepared powders were compared to those of the commercial boron serving as the starting material. The tapped density of the prepared spherical powders was much greater than that of starting boron indicating an improved flowability. The thermally activated oxidation for the spherical powders started at lower temperatures than for the starting boron. The intensity of the low-temperature reactions increased with an increased concentration of PTFE. The accelerated low-temperature oxidation correlated with reduced ignition temperatures measured for the composite powders coated on an electrically heated filament. In constant volume explosion experiments, substantially greater maximum pressures were measured for the spherical composite powders compared to the starting boron. The results suggest that the powder morphology tunable via the EAM plays the major role in improving its reactivity. The effect of the added PTFE is non-negligible but appears to be secondary. [ABSTRACT FROM AUTHOR]

For Ni-MH batteries, crystalline Mg-based alloys such as MgNi, Mg 2 Ni, REMg 12 , and La 2 Mg 17 are regarded as hopeful negative electrode materials. Even though these alloys are inexpensive and have promising discharge capacity, they hardly ever electrochemically absorb or desorb hydrogen at room temperature. In this paper, the MgNi-based Mg 50- x Ti x Ni 45 Al 3 Co 2 (x = 0, 1, 2, 3, 4) alloy electrodes were fabricated. The surface of the as-cast alloys was modified by mechanical Ni coating. The nanocrystalline and amorphous Mg 50- x Ti x Ni 45 Al 3 Co 2 (x = 0, 1, 2, 3, 4) + 50 wt%Ni alloys for Ni-MH batteries were prepared using mechanical ball milling. The effects of Ti content and ball milling time on the structure and electrochemical hydrogen storage properties of the alloys were investigated. The electrochemical testing reveals that the as-milled alloys can electrochemically absorb and desorb hydrogen well at room temperature. Without any activation, the milled alloys can achieve maximum discharge capacity in the first cycle. With the extension of ball milling time and the increase of Ti content, the cycle stability and discharge capacity of the alloys are significantly enhanced. The electrochemical impedance spectrum, high rate discharge ability, potentiodynamic polarization curve, and potential-step measurement all indicate that the electrochemical kinetics of the prepared alloys initially increase and subsequently decrease with the increase of Ti content, while significantly improve with the prolongation of milling time. • The Mg 50- x Ti x Ni 45 Al 3 Co 2 (x = 0, 1, 2, 3, 4) alloy electrodes were treated by mechanical ball milling. • The as-milled alloys can electrochemically absorb and desorb hydrogen well at room temperature. • The cycle stability and discharge capacity of the alloys are improved with the increase of milling time and Ti content. [ABSTRACT FROM AUTHOR]

• Together with mechanical milling and SPS method, we fabricated Ge 40 As 40 Se 20 glasses and studied their optical transmission and Vickers hardness. • With ball milling time of 50 h and sintering pressure of 37.5 MPa, an optimal Ge 40 As 40 Se 20 sintered glass with large Vickers hardness of 369 kgf/mm2 and high transmission of ∼43 % was obtained. • The size and number of pores presented in sintered glasses significantly affect the infrared transmission. In order to overcome the narrow glass-forming compositional range with traditional melt-quenching method, we here performed the mechanical milling and Spark Plasma Sintering technology to fabricate a high Ge content chalcogenide glass, the Ge 40 As 40 Se 20 glass, which locates edge of the Ge-As-Se glass-forming domain. By using the optimal ball milling time of 50 h and sintering stress of 37.5 MPa, the large size Ge 40 As 40 Se 20 bulk glasses were obtained, which possesses both a large Vickers hardness of 369 kgf/mm2 and a relative high infrared optical transmission of 43 % (@5 and 9 μm). Moreover, it was found there are pores in the sintered glasses more or less, and the pore size and number significantly affect the transmission, i.e., the optimal Ge 40 As 40 Se 20 bulk glasses were demonstrated has the smallest and least pores via scanning electron microscope. The combination of mechanical milling and low-temperature sintering methods has been confirmed can be used to improve the glass formability and then obtain the high Ge content component with a potential high hardness glass to break through the limited mechanical property of chalcogenides. [ABSTRACT FROM AUTHOR]

In this work we report the bandgap tuning of pseudoboehmite achieved by high energy ball milling. The milling process of pseudoboehmite was performed using a SPEX 8000 mill for of up to 10 h. Pseudooehmite powders were characterized before and after milling by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS). XRD results confirmed that the pseudoboehmite structure is preserved for 10 h of milling. The crystallite size of pseudoboehmite was estimated by Scherer equation, observing a constant increase with milling time from 2.72 nm to 3.18 nm. The pseudobohemite has a reduction in d-spacing with milling in the " c-axis ", but an enlargement in the " a-b directions ". The " c-axis " modification is due to water release, while the " a-b-plane " enlargement is attributed to cold welding during milling. The XPS and EELS analyses demonstrated a bandgap tuning effect from 7.11 eV to 6.20 eV in the raw and milled pseudoboehmite for 10 h. The results were demonstrated analytically. [ABSTRACT FROM AUTHOR]

Lignin, the second most abundant biopolymer in earth, represents nature's largest carbon sources, has high polydispersity and uncertain reactivity, that limit efficient modification/degradation and use of products obtained. In order to decrease by mechanochemical means the average molecular mass and polydispersity of lignin fragments of the CIMV organosolv lignin named Biolignin™, we applied a sodium hydroxide-assisted planetary ball milling process. Experimental conditions were first optimized on purified Biolignin™ then to Biolignin™ without prior purification in 20 mL jars before applying it successfully to a 500 mL planetary ball milling apparatus. Extensive, quantitative HSQC NMR, IR and GPC studies, overtaken supported our three most important findings: reduction of the needed quantity of sodium hydroxide of 75 % compared to the literature, obtention of halve (-51 %) the occurrence of β-O-4' linkages in lignin fragment, an optimum of 14 wt% of moisture is useful in the degradation process. • Mechanochemical degradation of lignin avoiding the recombination of fragments. • Optimization of sodium hydroxide quantities. • Recovery of a fraction composed of trimers of lignin. [ABSTRACT FROM AUTHOR]

Fe, Si and B powders, mixed with atomic composition Fe 78 Si 9 B 13 , are subjected after arc melting to a melt spinning process, which is optimized to obtain the greatest amount of amorphous ribbon. The amorphous ribbons are milled to powder form in a vibratory ball mill and a vibratory disc mill, taking care of maintaining the amorphous character. Ribbons and powders have been characterized by X-ray diffraction (XRD), laser diffraction, SEM and TEM microscopy, and differential scanning calorimetry (DSC). The amorphous character and particle size of the powders are characterized as a function of the mill charge and the milling time. It is shown that the use of the ball mill is appropriate for obtaining small quantities of amorphous or nanocrystalline powder, while the disc mill can process larger quantities of powder in a shorter time. The particle sizes obtained for milling times between 10 and 150 min range between 26 and 412 μm, ready for use in powder metallurgy processes. [Display omitted] • Production of amorphous powder by mechanical milling of ribbon. • Use of vibratory disc and ball mill for Fe 78 Si 9 B 13 ribbon milling. • Amorphous powder with a d (0.5) = 47 μm in 150 min with a vibratory disc mill. • Amorphous powder with a d (0.5) = 48 μm in 90 min with a vibratory ball mill. [ABSTRACT FROM AUTHOR]

RE-Mg-Ni alloy is considered a highly promising anode material for the next generation of MH-Ni batteries. However, the low cycle life, fast performance, and high manufacturing cost of this ideal MH-Ni battery anode material have become obstacles to its optimization. In this work, an as-cast La 0.7 Sm 0.3 MgNi 3.6 Co 0.4 superlattice alloy was prepared by vacuum medium frequency induction melting. Then, La 0.7 Sm 0.3 MgNi 3.6 Co 0.4 + 10 wt% Ni (0–2 h) composite hydrogen storage alloys with excellent properties were prepared by adding a catalyst (Ni) and conducting ball milling. XRD, SEM, and HRTEM were conducted to analyse the phase compositions, microstructures and macrostructures of the samples. The experimental results showed that with the increase in ball milling time, the microstructural characteristics of the alloy changed, such as the phase abundance, grain refinement, particle size reduction, and amorphous structure increase, directly leading to the change in electrochemical performance. The discharge capacity (C max) of the sample decayed from 264.0 mAh/g to 219.1 mAh/g, the cycle stability (S n) gradually increased with the extension of the grinding time, and the rate discharge performance first increased and then decreased. When the grinding time was 1 h, the best performance was HRD 900 = 36.53%. The critical factors affecting the dynamic performance, such as the charge transfer resistance (R ct), limiting current density (I L), and hydrogen diffusion coefficient (D), all exhibited the same trend and reached their respective optimal values at 1 h. • The influence mechanism of nanocrystalline-amorphous change on electrochemical performance was explored. • The capacity fading mechanism of ball milling on RE-Mg-Ni-based alloys was explored. • The comprehensive electrochemical properties of RE-Mg-Ni-based alloys are improved. [ABSTRACT FROM AUTHOR]

Magnesium-based wastes were reprocessed by mechanical milling under air atmosphere and used to produce hydrogen by hydrolysis on a laboratory scale. The evolution of the material during reprocessing and the generation of hydrogen in a 0.6 M MgCl 2 aqueous solution at 24 °C are reported. The morphology, microstructure and phase abundance change with milling time. During mechanical processing, (i) particle size and crystallite size reduce, (ii) microstrain accumulates in the material, (iii) Al dissolves in Mg, (iv) the amount of Mg 17 Al 12 (β-phase) increases and (v) small quantities of Fe from the milling tools are incorporated in the material. By hydrolysis, hydrogen yields in the 70–90% range after 30 min of reaction have been obtained, depending on milling time. Reactants are not exhausted during the hydrolysis reaction in the saline solution, due to the formation of a Mg(OH) 2 layer that produces a passivating effect. Higher generation has been observed for larger particles and for materials reprocessed for longer milling times. Reaction kinetics also improves with milling time, with faster rates observed for the smaller particles. The shape of the hydrolysis curves can be fitted with a model that corresponds to a reaction limited by a three dimensional geometric contraction process. Mg 17 Al 12 and Fe favor hydrogen production by acting as micro-galvanic cathodes during the reaction. • By milling in air, Mg chips were reprocessed at lab scale to produce H 2 by hydrolysis. • H 2 yields in the 70–90% range were obtained using a 0.6 M MgCl 2 solution. • 100 mL of H 2 per gram of material were released in the first 1–2 min. • Reaction kinetics is controlled by a geometric contraction process. • Mg 17 Al 12 and Fe favor hydrogen production by acting as micro-galvanic cathodes. [ABSTRACT FROM AUTHOR]

In this paper, the TiFe-based master alloy Ti 1.04 Fe 0.7 Ni 0.1 Zr 0.1 Mn 0.1 Pr 0.06 was fabricated by conventional induction melting with high purity helium as the protective gas. After that, the as-cast specimens were mechanically milled with nickel powders to synthesize the as-milled Ti 1.04 Fe 0.7 Ni 0.1 Zr 0.1 Mn 0.1 Pr 0.06 + 10 wt.% Ni composites with excellent electrochemical characteristics. The master alloy is composed of TiFe, Ti 2 Fe and Pr phases, which has a typical crystal structure. Mechanically milling the master alloy with nickel powder leads to the reductions of the grain size and particle size, even forming amorphous structure. The experimental results showed that the specimens after ball-milling treatment can be used to hydriding and dehydriding by electrochemistry, getting the maximal discharge capacity in the first cycle, and no activation was required. The discharge capacity of the as-milled composites declined from 264.2 to 133.6 mAh/g with the milling duration extending from 5 to 30 h. The electrochemical kinetics markedly declined with prolonging milling duration. However, the electrochemical cycling stability of the specimens reduced firstly and then increased with the prolongation of grinding duration. • The ferrotitanium alloy +10 wt.% Ni were prepared by mechanical milling. • The as-milled (5 h) specimen has the maximal discharge capacity of 264.2 mAh/g. • The electrochemical kinetics are worse with the prolongation of milling duration. [ABSTRACT FROM AUTHOR]

Body-centered cubic (BCC) alloys are considered as promising materials for hydrogen storage with high theoretical storage capacity (H/M ratio of 2). Nonetheless, they often suffer from sluggish kinetics of hydrogen absorption and high hydrogen desorption temperature. Carbon materials are efficient hydrogenation catalysts, however, their influence on the hydrogen storage properties of BCC alloy has not been comprehensively studied. Therefore, in this paper, composites obtained by milling of carbon catalysts (carbon nanotubes, mesoporous carbon, carbon nanofibers, diamond powder, graphite, fullerene) and BCC alloy (Ti 1.5 V 0.5) were extensively studied in the non-hydrogenated and hydrogenated state. The structure and microstructure of the obtained materials were studied by scanning and transmission electron microscopes, X-ray diffraction (XRD), and Raman spectroscopy. XRD and Raman measurements showed that BCC alloy and carbon structures were in most cases intact after the composite synthesis. The hydrogenation/dehydrogenation studies showed that all of the used carbon catalysts significantly improve the hydrogenation kinetics, reduce the activation energy of the dehydrogenation process and decrease the dehydrogenation temperature (by nearly 100 K). The superior kinetic properties were measured for the composite with 5 wt % of fullerene that absorbs 3.3 wt % of hydrogen within 1 min at room temperature. [Display omitted] • Mechanical milling without milling balls prevents serious damage of carbon additives. • BCC alloy catalysed by fullerene absorbs 3.3 wt% of hydrogen within a minute. • The addition of carbon catalysts decreases the dehydrogenation temperature by 100 K. • The dehydrogenation process activation energy is twice reduced in studied composites. [ABSTRACT FROM AUTHOR]

Spherical boron powders with sizes ranging from 4 to 100 μm were prepared by ball milling a commercial boron powder. A planetary mill was used with a process control agent consisting of two immiscible fluids: hexane and acetonitrile. The spherical powders formed when the volume of the loaded boron was close to that of acetonitrile in presence of excess hexane. Particle sizes were measured using low-angle laser light scattering, they were examined using scanning electron microscopy, and their specific surface area was measured using nitrogen adsorption. The size distributions of the prepared spheres were much narrower than is common for solids processed by high-energy milling. Spherical particles were fragile; their mechanical stability was improved when a small amount of Fluorel®, a fluorocarbon binder, was preliminarily dissolved in acetonitrile. Experiments showed that the prepared spherical powders exhibited a higher bulk density and much better flowability than starting boron powder. Process-property relations were explored by systematically varying milling parameters and analyzing their effect on the size distribution of the formed spheres. The size of spherical particles was found to decrease with the decrease in the amount of acetonitrile used; it was also decreased with an increase in milling time, number of milling balls, and speed of milling. [Display omitted] • Mechanical milling in immiscible liquids yields spherical boron powders • Size distributions of the obtained spherical powders are symmetric and narrow • Particle sizes are controlled by the ratio of liquids, milling time and intensity • Spherical boron powders flow and pack much better than commercial boron • Process-property relations are described quantitatively by a data-based model [ABSTRACT FROM AUTHOR]

The facile synthesis of ytterbium tetrahydroaluminate Yb(AlH 4) 3 is conducted by a mechanochemical procedure under hydrogen atmosphere for the first time. Results show that the synthesized Yb(AlH 4) 3 remains as an amorphous state. The thermal decomposition of Yb(AlH 4) 3 goes through a four-stage pathway with several amorphous intermediate phases during the process. The first dehydrogenation step of Yb(AlH 4) 3 presents a relatively low apparent activation energy of 99.6 kJ mol−1, and ninety percent of the hydrogen from this stage can be liberated within 20 min at 160 °C. Rehydrogenation tests above 160 °C and 14 MPa hydrogen pressure demonstrate the unsuccessful rehydrogenations of the first decomposition step due to the formation of a thermodynamically more stable compound YbHCl. • A novel transition metal alanate Yb(AlH 4) 3 is prepared. • A solvent-free mechanochemical procedure is developed. • Yb(AlH 4) 3 remains as an amorphous state. • The thermal decomposition goes through a four-stage pathway. • The first dehydrogenation step presents a low apparent activation energy. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mechanical milling (MM) decreased the crystallite size of tungsten down to 32 nm. • Higher MM-times fostered the tungsten incorporation in the (Cr, W) solid solution after hot–pressing. • A higher tungsten solubility in the solid solution correlated with a higher microhardness. Based on the significantly different melting points and high oxygen affinities, the fabrication of chromium-based tungsten silicides is restricted to powder metallurgical production routes. To foster particle contacts and diffusion processes between chromium and tungsten, which are known to necessitate long sintering times, mechanical alloying or milling processes prior to sintering are established. Nonetheless, due to spinodal decomposition of Cr and W, the solid solution formation is complex and yet little understood. For this reason, the influence of the mechanical milling time (0–24 h) on the crystal structure and the microstructural properties of hot-pressed 60Cr30W10Si (wt.–%) is examined. In this context, two different powders containing a different tungsten particle size (0.8 and 3 µm) were mechanically alloyed to analyze the impact on the phase formation and the particle distribution in the microstructure. It was shown that mechanical milling supported the mechanical clamping between the particles. However, the increased milling times significantly decreased the crystallite sizes of the particles and fostered the tungsten solubility in the Cr-rich (Cr, W) solid solution formed during sintering, thus supporting the densification. [ABSTRACT FROM AUTHOR]

[Display omitted] • FeCrAl-ZrC alloy has an uniform grain structure with an average grain size 0.86 μm. • FeCrAl-ZrC alloy display higher high-temperature strength more than 110 MPa at 800 ℃. • Hall-Petch and dispersion strengthening are the main strengthening mechanism. • Good interface bonding between Fe and ZrC are also main strengthening mechanism. Low mechanical strength, especially at high temperatures, is the key problem that limit the application of FeCrAl alloys as the accident tolerance fuel (ATF) cladding materials. Dispersion strengthening by carbide nanoparticles is an effective way to improve mechanical properties at high temperatures. In this work, an ultrafine grained FeCrAl-0.6 wt.% ZrC alloys with excellent mechanical properties were fabricated successfully by mechanical milling and spark plasma sintering. The effect of milling speed on powder characteristics, microstructure and mechanical properties of FeCrAl alloys were investigated. The particle size of the powders increase significantly after milling at 400 rpm, while it has a lower oxygen content. Increasing the milling speed decreased the resultant grain size and improved relative density. Transmission electron microscope (TEM) demonstrated the nano ZrC particles uniformly distributed in the matrix at higher milling speed, which effectively promotes grain refinement and dispersion strengthening. The results of mechanical properties show that the tensile strength, percentage elongation and hardness of FeCrAl-0.6 wt.% ZrC alloys at room temperature (RT) reached up to 1.05 GPa, 349.86 HV and 12.1%, respectively, after milling at 400 rpm. It is worth noting that the FeCrAl-0.6 wt.% ZrC alloy also exhibited a good high-temperature strength more than 110 MPa at 800 ℃, which is about 55.4% and 24.7% higher than previously reported FeCrAl-0.5 wt.% ZrC and FeCrAl-1.0 wt.% ZrC alloys, but the plasticity is reduced. The results demonstrated that the excellent mechanical properties were not only attributed to the dispersion strengthen by nanosized ZrC, a good interface bonding between Fe matrix and nanosized ZrC, but also the ultra-fine grained structure induced by the milling process. [ABSTRACT FROM AUTHOR]

The goal of this work was to separate the reaction and spark plasma sintering (SPS) effects during the in-situ synthesis of TiC in mechanically milled Ti–C–3Cu powder mixtures. The powders were milled for 3–10 min in a high-energy planetary ball mill. Structural changes occurring in the reaction mixtures during thermal explosion (TE) in a furnace and SPS in a graphite die were compared. Although the maximum temperature of TE reached the melting point of copper in some samples, no evidence of extensive melting was observed in the microstructure of the products of TE. The ignition and maximum temperatures of TE were found to decrease with increasing milling time of the mixture. In the mixture milled for 10 min, the maximum temperature of TE was only 820 °C. Melting of copper at the inter-particle contacts during SPS was observed in samples milled for 5–10 min (SPS at 900–980 °C) and caused the formation of TiC-depleted regions in the microstructure. Those regions were the re-solidified melt partially filling the pores between the agglomerates. Based on the analysis of the TE parameters in the mixtures and microstructures of the products of TE and SPS, melting during SPS was attributed to the effect of electric current (a high electric current density at the inter-particle contacts) and not to the heat of reaction. The hardness, compressive strength and Young's modulus of the sintered composites are reported. A TiC–Cu composite (milling time 5 min, SPS at 980 °C, relative density 93%) shows a compressive yield strength of 890 MPa and an ultimate compressive strength of 920 MPa. [ABSTRACT FROM AUTHOR]

This study introduced a novel method for incorporating microstructural and mechanical heterogeneity into Ti–Zr–Nb alloy to improve its strength without significantly affecting the elastic modulus. Ti–Zr–Nb alloy powder was milled at different ball-milling energies using a planetary ball mill, mixed with parent pristine powder in equal weight fractions using a horizontal ball mill, and sintered using spark plasma sintering. The resulting bimodal-like microstructure showed an increase in tensile yield strength (up to 410 MPa) without significant changes in the elastic modulus (<6 GPa). Milling followed by sintering caused grain refinement and precipitation in the relevant zones of the sintered samples, resulting in a heterogeneous structure due to the unique spread of α-precipitates. The strength of the heterogeneity-incorporated alloys was improved as a function of milling while maintaining high plasticity and a low elastic modulus. [Display omitted] • The innovative method boosts Ti–Zr–Nb strength without huge elastic modulus change. • Tensile strength enhancement achieved through unique microstructural heterogeneity. • SPS induces partial grain refinement and α-precipitates for heterogeneous structure. • The TRIP mechanism was no longer active in precipitated alloys. [ABSTRACT FROM AUTHOR]

The concept of high entropy alloys (HEAs) is an emerging subject in materials science and engineering. The presence of at least four elements in equiatomic or near equiatomic composition in HEAs has led to superior properties and vast unexplored alloying space. In this study, we investigated two new HEA powders, AlCoCuMnNi and Al 0.25 CoCuMnNi, by subjecting mechanically milled (MM) powders to a series of analyses over a 60 h ball milling process. It was found that alloying starts after 20 h of MM and after 45 h, full elemental integration into the host lattice was detected. Meanwhile, further milling to 60 h can cause powder contamination. The High-Resolution Transmission Electron Microscopy (HRTEM) results validated the XRD findings and provided further insights into the substantial influence of Al content on the microstructure and the extent of amorphization within the milled powders. Differential Thermal Analysis (DTA) analysis on the MM powders showed one exothermic peak for AlCoCuMnNi and one for Al 0.25 CoCuMnNi at high temperatures, which may suggest the formation of the BCC or second FCC phases for these alloys. The results confirmed the significant influence of the increased Al content on increasing both the lattice constant and lattice strain while decreasing thermal stability of the investigated MM powders. The present results provided insights needed for consolidation of such HEA powders. [Display omitted] • Mechanical alloying utilized to develop AlCoCuMnNi and Al0.25CoCuMnNi new HEAs. • Morphology, microstructure, and thermal behavior of milled powders examined. • Single phase FCC solid solution formed after 20 h milling for these alloys. • Higher lattice distortion in AlCoCuMnNi accelerated grain refinement. • Enhanced thermal stability observed in Al0.25CoCuMnNi due to reduced lattice strain. [ABSTRACT FROM AUTHOR]

The solid-state electrolyte β -PbSnF 4 has been reported to have the highest fluorine-ion conductivity at room temperature among four different structures of the monoclinic (α), orthorhombic (o), cubic (γ), and tetragonal (β) at steady state. Therefore, finding an effective way to prepare β -PbSnF 4 or to transform β -PbSnF 4 from other phases is a research hotspot in FIBs. In particular, the transition mechanisms between γ -PbSnF 4 and β -PbSnF 4 are still unclear in the reported literature because the influence of trace moisture is ignored in previous research, which always leads to controversial conclusions about the phase transition mechanism. Previous articles have reported that γ -PbSnF 4 can only be transformed into β -PbSnF 4 by aging at a high temperature above 100 °C. However, this work shows that the transition from γ -PbSnF 4 to β -PbSnF 4 can occur at room temperature. Moisture is the critical factor in inducing the phase transition from γ to β -PbSnF 4. The resulting β -PbSnF 4 has a high fluoride-ion conductivity of 8.1 × 10−4 S cm−1, while the solid electrolyte for an all-solid-state FIB with BiF 3 as the cathode and Sn as the anode has a maximum discharge capacity of 55.8 mAh g−1 at 120 °C. [Display omitted] • γ -PbSnF 4 can be converted into β -PbSnF 4 at room temperature. • The moisture can induce the phase translation. • A high fluoride ion conductivity of 8.1*10−4 S cm−1 is achieved. • The protons in the H 2 O can trigger the rearrangement of the F atoms. [ABSTRACT FROM AUTHOR]

Constructing heterojunctions with oxygen defect-rich structures and abundant phase interfaces poses an appealing yet challenging task in the development of non-precious metal oxide catalysts for formaldehyde (HCHO) oxidation. Herein, we present a simple and efficient method for fabricating highly active manganese oxide heterojunction catalysts for HCHO oxidation. This method involves the hydrothermal synthesis of a nanostructured α-MnO 2 /γ-MnOOH composite, followed by mechanical milling-induce phase transformation of γ-MnOOH to Mn 2 O 3. Importantly, mechanical milling not only creates the heterojunction but also imparts oxygen defect-rich structures and an abundant phase interface to the catalyst. The resulting α-MnO 2 /Mn 2 O 3 heterojunction exhibits outstanding performance in HCHO oxidation, comparable to the best non-precious metal oxide catalysts reported thus far. It achieves a 100% conversion of 100 ppm HCHO under a gas hourly space velocity of 120 L g cat −1 h−1 at 80 °C, corresponding to a mass-specific reaction rate of 8.92 μmol g−1 min−1 and an area-specific reaction rate of 0.18 μmol m−2 min−1. Based on the control experiments using in situ diffuse reflectance infrared Fourier transform spectroscopy combined with online gas chromatography, we gained insights into the mechanism of HCHO oxidation over the α-MnO 2 /Mn 2 O 3 catalyst and the functional roles played by its component phases. [Display omitted] • The α-MnO 2 /Mn 2 O 3 heterojunction is prepared by a simple two-step method. • Mechanical milling induces the phase transformation from γ-MnOOH to Mn 2 O 3. • Milling easily produces oxygen defect-rich structures and abundant phase interfaces. • The α-MnO 2 /Mn 2 O 3 heterojunction shows high activity for HCHO oxidation. [ABSTRACT FROM AUTHOR]

The synthesis, thermodynamic destabilisation and hydrogen sorption properties of the M 0.2 Ca 0.8 MgH 4 hydride system, where (M = Na or Li) have been investigated. Samples were mechanically milled under argon for 5, 10 and 15 h; then characterised by X-ray diffraction (in/ex-situ), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) coupled with a mass spectrometer (MS). On Li and Na substitution into Ca–Mg–H ternary hydride, diffraction peaks shifted to higher angles. 2 and 3 endothermic reactions were observed for the Li 0.2 Ca 0.8 MgH 4 and Na 0.2 Ca 0.8 MgH 4. The maximum amount of hydrogen release was achieved for the 5 h milled Na 0.2 Ca 0.8 MgH 4 hydride from 298 °C to 386 °C accounting for 3.5 wt % of H 2. • M 0.2 Ca 0.8 MgH 4 (M = Na, Li), was prepared by mechanical milling under argon alone. • Li 0.2 Ca 0.8 MgH 4 samples show a lattice contraction in the main Ca 19 Mg 8 H 54 phase. • 3.5 wt % of H 2 at 329 °C was achieved on the 5 h milled Na 0.2 Ca 0.8 MgH 4. • Li and Na incorporations enhance the sorption properties of Ca–Mg–H hydride. [ABSTRACT FROM AUTHOR]

• Ti and Y 2 O 3 powders were chosen to study the formation mechanism of Y-Ti-O oxides. • TiO 2 , rather than other titanium oxides, was reacted with Y 2 O 3 to form Y 2 Ti 2 O 7. • Oxygen concentration affects the oxidation of Ti and the formation of Y 2 Ti 2 O 7. • The formation of Y 2 Ti 2 O 7 was began at about 500 ℃ and completed around 1004. • The maximum formation rate of Y 2 Ti 2 O 7 occurred at 779. Y-Ti-O nano-scale oxides play important roles in ensuring the excellent performance of oxide dispersion strengthened (ODS) steels. In this study, a model powder system of Y 2 O 3 and Ti was designed to investigate the formation and evolution mechanism of Y-Ti-O oxides. The morphology of powders tended to be stable after high energy ball milling for 240 min in Ar. X-ray diffraction (XRD) results suggested that there was no formation of new phase after mechanical milling. Thermo-gravimetric and differential thermal analysis (TG-DTA) was applied to analyze physical and chemical reactions of milled powders respectively in Ar and air. The corresponding annealing and XRD were performed to study the types and structures of oxides at different temperatures. It shows that oxygen concentration and temperature are the critical factors affecting the formation of oxides. Ti was evolved into Ti 6 O, Ti 3 O and TiO 2 in turn with temperature increasing. Then only TiO 2 was reacted with Y 2 O 3 to form Y 2 Ti 2 O 7. The formation of Y 2 Ti 2 O 7 began at around 500 ℃ and was completed around 1004 ℃. A maximum formation rate occurred at about 779 ℃. High resolution transmission electron microscopy (HRTEM) suggested that the main phase in powders sintered at 1100 ℃ was identified as pyrochlore structure Y 2 Ti 2 O 7. [ABSTRACT FROM AUTHOR]

Wet mechanochemical processing of olivine under a CO 2 atmosphere promotes the CO 2 sequestration in the form of MgCO 3 and the CO 2 reduction to CH 4 at room temperature. The effects of milling time and CO 2 pressure on the CO 2 storage and CO 2 reduction were evaluated at lab-scale. Wet mechanochemical introduces progressively significant morphological, structural, microstructural, and textural changes in olivine for prolonged milling times, inducing fast carbonation reaction after 15 min of ball milling. Long milling times stimulate the CO 2 conversion to CH 4 and decrease the carbonation reaction rate, because both reactions occurred simultaneously. The CO 2 sequestrated as MgCO 3 is about 4.83 wt% and 6.81 wt% for 1.0 atm of CO 2 after 120 min and 180 min of milling using different CO 2 charge strategy. The amount of CO 2 reduced to CH 4 was 24 and 33 mmoles/kg of olivine after 120 min with 1.0 and 1.5 atm of CO 2 , respectively. Wet milling of olivine in CO 2 atmosphere is a technique with potential for large-scale carbon mineralization. Unlabelled Image [ABSTRACT FROM AUTHOR]

Shock-induced reactions were investigated in boron (B) – metal nitride (MeN: Me=Ga, Zr, Cr) exothermic systems. All considered powder mixtures were initially mechanically treated in a high-energy ball-mill to fabricate B-MeN nanostructured composite particles, which were subsequently shock loaded using an explosive charge. The structures of these materials were analyzed by conventional and synchrotron X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. It was discovered that shock-induced reactions in the GaN+B system resulted in the formation of the metastable wurtzitic form of boron nitride (w-BN). This directly implies that ultra-fast (0.5–5 μs) reactions took place under the high-pressure conditions of the shock wave. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The addition of nickel as catalyst and particle size reduction through milling process is considered as the best approach for MgH 2 properties to be thermodynamically and kinetically more favorable. The recent development in MgH 2 is done by adding Ni (14–16 wt%) and particle size reduction through simple mechanical milling at a large sample of 100 g. The research sequences are easy to adopt for the implementation and sustainable research of MgH 2. Starting from the moisture test to the milling process, continue with particle size distribution (PSD) for the milled sample and final moisture test after PSD. Some critical finding from our research includes high capacity storage of Mg 84 :Ni 16 above 5 wt% H 2 within 20 min at 573 K, the effect of moisture content on system performance and the different effect of carbon (C) in the system at specific temperature and pressure that may have. Image 1 • High storage capacity of MgH 2 up to 5 wt% by adding 16 wt% Nickel. • Clear evidence of the effect of moisture content in MgH 2 performance. • A unique behavior of MgH 2 after adding 5 wt% C at specific pressure and temperature. • Ease of process to improve MgH 2 system for large sample capacity. [ABSTRACT FROM AUTHOR]

The Mg–Ni-based alloy La 9 Ce 1 Mg 80 Ni 5 was fabricated by a vacuum induction furnace with high purity helium gas. The surface modification of the as-cast alloys was operated by mechanical coating Ni and graphite (GR). The composites La 9 Ce 1 Mg 80 Ni 5 -200 wt% Ni- x wt.% GR (x = 0–4) with nanocrystalline and amorphous structures were synthesized by mechanical milling. Adding appropriate GR brings on the enhancement of ball-milling efficiency and inhibits the agglomeration of alloy powders. Furthermore, the discharge capacity of the composites obtains the maximal values with an optimized GR percentage. Increasing GR content from 0 to 4, the capacity retention rate at 20th cycle (S 20 = C 20 / C max) of the 20 h milled composite improves from 72.2% to 74.3% and that of the 80 h milled specimen changes from 54.4% to 56.9%. Electrochemical tests indicate that with the optimization of GR percentage, the composites can get the best electrochemical kinetic property, such as the highest HRD value, the highest hydrogen diffusion coefficient and the lowest charge transfer resistance. • The La 9 Ce 1 Mg 80 Ni 5 –Ni–GR composites were synthesized by mechanical milling. • Graphite is beneficial to the improvement of electrochemical characteristics. • The composite La 9 Ce 1 Mg 80 Ni 5 -200 wt% Ni-3 wt.% GR has the optimal property. [ABSTRACT FROM AUTHOR]

Element replacement and mechanical milling are considered as the most effective ways to improve Mg-based alloys in their hydrogen storage performance. The as-milled La 7 RE 3 Mg 80 Ni 10 (RE = Sm, Ce) alloys were prepared in this experiment by introducing both element replacement (replacing La by Ce or Sm partially) and mechanical milling technologies. The influence made by different replacing elements on the structure and hydrogen storage property of La 7 RE 3 Mg 80 Ni 10 (RE = Sm, Ce) alloys was investigated in detail. X-ray diffraction, transmission electron microscope, automatic Sievert apparatus, thermogravimetry and differential scanning calorimetry were used to investigate the experimental alloys. The experiment reveals that a nanocrystalline and amorphous structure appears after mechanical milling. Moreover, comparing with the RE = Sm alloy, the RE = Ce alloy has a superior hydrogen desorption property, including larger hydrogen absorption capacity, faster hydriding/dehydriding rate, lower onset hydrogen desorption temperature, and lower dehydrogenation activation energy. • La 7 RE 3 Mg 80 Ni 10 (RE = Sm, Ce) alloys were prepared by ball milling. • Substituting La by Sm or Ce does not change the microstructure of alloys. • Replacing La by Ce weakens the stability of alloys more effectively then by Sm. • RE = Ce alloy shows better hydrogen desorption kinetics than RE = Sm alloy. [ABSTRACT FROM AUTHOR]

Fine powder dispersions of MgH 2 - TiH 2 composites were obtained through different manufacturing routes using reactive mechanical grinding. The as prepared powder dispersions were subjected to hydrogen sorption kinetics and the results clearly revealed a heterogeneous kinetic nature already reported in nanocrystalline MgH 2. The differences observed in the heterogeneous kinetic of isothermal kinetics reveal a strong dependence on grain boundaries microstructure of the prepared hydrides. The basic findings described here suggest the need for studies to understand how the superposition of complex mechanisms are involved in kinetics regarding the microstructure. • Heterogeneous kinetic sorption properties of mechanically prepared Mg–Ti hydrides. • Repetitive milling route of (MgH 2) 80 -(TiH 2) 20 powder nanocomposites was achieved. • Previous evidence on equal composites led to the research of heterogeneous kinetic. • Hydrides with the same phases exhibit different heterogeneous kinetic properties. [ABSTRACT FROM AUTHOR]

The six possible equiatomic five-transition metal High Entropy Carbides (HECs) of the IVB (Ti, Zr, Hf) and VB (V, Nb, Ta) groups of the periodic table, i.e., TiZrHfVNbC 5 , TiZrHfVTaC 5 , TiZrHfNbTaC 5 , TiZrVNbTaC 5 , TiHfVNbTaC 5 and ZrHfVNbTaC 5 , were successfully obtained via a powder metallurgy route at room temperature, specifically, by one-step diffusion mechanosynthesis starting from the elemental constituents (using graphite as the carbon source). Three of those HECs, TiZrHfVTaC 5 , TiZrVNbTaC 5 and ZrHfVNbTaC 5 , were developed for the first time. Their development was possible without any subsequent thermal treatment, in contrast to the usual way (reactive sintering at 1800–2200 °C), and in a powder form, make them potential advanced raw ceramics for hard, refractory and oxidation resistance coatings or matrix phase composites. [ABSTRACT FROM AUTHOR]

• Milling-driven AsS amorphization in multi-particulate β -As 4 S 4 -based grinding media. • Coexistence of milling-induced nanocrystalline nc- β -As 4 S 4 -and amorphous a-AsS phases. • High-energy milling-driven AsS amorphization by molecular-to-network transition. • Milling-assisted vitrification of nc- β -As 4 S 4 essentially governed by grinding media. • The crucial role of ZnS-assisted AsS amorphization in 1⋅β-As 4 S 4 -4⋅ZnS-1⋅Fe 3 O 4 medium. Amorphization scenarios in multiparticulate grinding media composed of As 4 S 4 /ZnS/Fe 3 O 4 nanocomposites driven by high-energy ball mechanical milling are identified employing the X-ray powder diffraction analysis on intermediate-range ordering in the generated amorphous phase. This amorphous phase is supposed to be nucleated heterogeneously from grain boundaries of β -As 4 S 4 crystallites followed by penetration deeply into grain interior, stabilizing the crystalline-amorphous core-shell structure of the fine-grained nanoparticles. Coexistence of nanocrystalline nc- β -As 4 S 4 and amorphous arsenic monosulphide a-AsS phases is crucial feature of these nanocomposites, the amorphous substance being generated continuously due to re-amorphization of disordered phase initially existed in arsenic sulphide prepared by synthesis from elements and direct milling-driven vitrification of nc- β -As 4 S 4. In monoparticulate β -As 4 S 4 -based and biparticulate As 4 S 4 /Fe 3 O 4 nanocomposites, the amorphizing configurations are composed of single- and triple-broken chain-like network clusters. Under stronger conditions realized in the grinding medium composed by hard nanoparticles biased by their sizes in respect to 20:1 rule, as in triparticulate 1⋅As 4 S 4 -4⋅ZnS-1⋅Fe 3 O 4 nanocomposite, the amorphization scenario differs being activated by double-breaking of intramolecular covalent bonds within As 4 S 4 cage-like molecules. This effect is identified as nanocrystalline nc-ZnS-assisted milling-driven arsenic monosulphide amorphization in triparticulate 1⋅β-As 4 S 4 -4⋅ZnS-1⋅Fe 3 O 4 nanocomposite solution. [ABSTRACT FROM AUTHOR]

Mg 2 (Fe, Cr, Ni)H X synthesis was successfully performed using magnesium hydride and 316L austenitic stainless steel. It was proven that despite being widely used and considered inert, under some conditions, this steel could react with magnesium hydride and be used as a reaction substrate for complex hydride synthesis. The properties of the product are different from those of pure Mg 2 FeH 6, which suggests the partial substitution of iron atoms with chromium and nickel. The influence of milling time on hydrogen content and phase composition was studied and compared to the reference material. It was found to be likely that mechanically induced martensite formed in austenitic stainless steel during ball milling may enable the reaction between steel and magnesium hydride. Image 1 • Magnesium hydride reacts with austenitic stainless steel during ball milling. • The reaction is preceded with mechanically induced martensite formation. • Properties of the product are different from those of pure Mg 2 FeH 6. [ABSTRACT FROM AUTHOR]

Micron-sized composite particles consisting of an Al-Mg alloy and Zr were produced via mechanical milling. Three different particle chemistries were prepared with varying ratios of the Al-Mg alloy to Zr. In addition, the prepared powders were size selected using mechanical sieves. Explosively launched combustion properties of these powders were independently measured as a function of the particle stoichiometry and particle size. Ignition temperatures were measured utilizing a heated filament experiment while combustion efficiency was characterized by measuring the dynamic pressure produced in a closed bomb in which the powder was explosively dispersed under fixed enthalpy conditions. Commercial Al powder, Valimet H-2, was also tested alongside these materials as a benchmark. High-speed video and thermocouple measurements were also obtained for the closed bomb experiments. We observed an increase in combustion efficiency from 30% to 80–90% in the composite materials compared to the pure Al. Furthermore, reaction products were collected and analyzed by powder x-ray diffraction to gain further insight into combustion efficiency and reaction pathways. We observed significant improvement of combustion under these experimental conditions, including higher quasi-static pressures and higher rates of pressure rise, with composite fuels compared to pure Al, even without a secondary oxidizer additive. [ABSTRACT FROM AUTHOR]

Ionic conductors composed of lanthanide-doped ceria with general formula Dy y Ce 1-y O 2-δ (y = 0.05, 0.1 and 0.15) were synthesized by mechanochemistry (mechanical milling), and their electrical properties analyzed to be used as solid electrolytes in low-temperature SOFC. Starting oxide reagents were milled at different times in a planetary mill and the evolution of their structures and phases with milling time and temperature (up to 1500 °C) was followed by XRD. Just milled powders were also uniaxially pressed and sintered at different temperatures (1200, 1350 and 1500 °C), and analyzed by FE-SEM, to explore their morphologies as a function of temperature and Dy content. The electrical properties of these materials and undoped commercial CeO 2 were analyzed by impedance spectroscopy at different temperatures (200–650 °C) and frequencies (100 Hz - 1 MHz). Results showed that mechanochemistry is a suitable method to obtain the Dy y Ce 1-y O 2-δ systems after 20 h of milling, since XRD patterns of these milled powders reveal the formation of fluorite-type cubic solid solutions for all studied compositions. Increasing of temperature generates a higher crystallinity in these materials while the absence of phase transitions in them is corroborated at 1200 °C. Analysis of electrical properties of samples sintered a 1200 °C corroborates the viability of these systems to be used as solid electrolytes in the SOFC technology, being that high dc conductivities (σ dc) were obtained for all doped samples, especially for the composition Dy 0.1 Ce 0·9 O 2-δ , which showed a σ dc = 1 × 10−1.91 S cm−1 at 650 °C. This value represents an increase of almost three orders of magnitude for this composition with respect to the undoped CeO 2 sample (y = 0, σ dc = 1 × 10 −4.83 Scm−1). • CeO 2 doped with Dy was successfully synthesized by a mechanochemical reaction. • All compositions (5, 10 and 15% mol of Dy) show a cubic fluorite-type structure. • Electrical properties of the samples were measured as a function of temperature. • Conductivity (σ dc) reaches a maximum of 1 * 10−1.91 Scm−1 (650 °C) for 10% of Dy. • Increasing of σ dc is related to the creation of oxygen vacancies in the structure. [ABSTRACT FROM AUTHOR]

In this paper, a novel Al–Bi(OH) 3 system hydrogen-generating material is investigated. Hydrolysis experiments show that the hydrolysis properties of the Al–10 wt% Bi(OH) 3 composite are significantly improved by doping with sodium chloride, and the Al–10 wt% Bi(OH) 3 –5 wt% NaCl composite has a low activation energy (10.4 kJ mol−1). With the further optimization of milling time, the hydrogen yield of Al–10 wt% Bi(OH) 3 –5 wt% NaCl composite reaches 1000 mL g−1 in 1 min. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive spectroscopy and thermogravimetric analysis are applied to characterize the composite and explore the hydrolysis mechanism. The characterization results show that the activation of aluminum mainly comes from three factors: (1) The formation of alumina during ball milling plays an important role in preventing the agglomeration between Al–Bi, Al–Al and Bi–Bi; (2) Bismuth generated during ball milling can form micro-galvanic cell with aluminum to promote the corrosion of aluminum; (3) Sodium chloride as a grinding aid contributes to crush aluminum powder, and chloride ions facilitate the corrosion of aluminum in the hydrolysis process. In addition, the drying method and initial water temperature have a great influence on by-products. The composite is expected to be used in mobile emergency fuel cell due to its rapid hydrogen production capacity. • The hydrolysis properties of Al–Bi(OH) 3 were significantly improved by doping with NaCl. • The chemical reactions of Al–Bi(OH) 3 –NaCl during milling and hydrolysis were inferred. • The hydrogen yield of Al–10 wt% Bi(OH) 3 –5 wt% NaCl composite reaches 1000 mL g−1 in 1 min. [ABSTRACT FROM AUTHOR]

• Y 2 O 3 amorphisation upon mechanical milling, without chemical decomposition. • Addition of Ti in the alloy has no effect on amorphisation of Y 2 O 3. • FeYO 3 oxide formed upon annealing of mechanically milled Fe-15Y2O3-xTi model alloy with Ti ≤ 2 wt%. • Y 1.6 Ti 1.8 Fe 0.4 O 6.6 evolved upon annealing of mechanically milled model ODS alloys with Ti ≥ 10 wt%. • Y 2 O 3 : Ti ratio of 1:1 is favorable for formation of fine dispersoid of Y 1.6 Ti 1.8 Fe 0.4 O 6.6. A model Oxide Dispersion Strengthened (ODS) alloy powder of composition Fe – 15 wt. % Y 2 O 3 – x wt. % Ti (x = 0, 2, 5, 10 and 15) were synthesized by high energy mechanical milling in Ar atmosphere for a prolonged duration of 60 h. Synchrotron X-ray diffraction (XRD) and transmission electron microscopy (TEM) observations suggested the amorphisation of Y 2 O 3 nano-crystallites, irrespective of Ti content, which is further studied by Raman spectroscopy. The Raman spectroscopy analysis confirms the presence of Y O bonding in the milled powder and ruled out the possibility of elemental dissociation of Y 2 O 3 and dissolution into the Fe matrix. Annealing of the milled powders containing different amounts of Ti led to formation of different types of oxide complexes which were also studied using synchrotron XRD and TEM studies. The role of Ti in refining the dispersoids through formation of Y 1.6 Ti 1.8 Fe 0.4 O 6.6 is established through these studies. [ABSTRACT FROM AUTHOR]

Thermite powders with molar composition 8Al·3CuO were prepared in two stages by Arrested Reactive Milling (ARM). In the first stage, the starting materials Al and CuO were milled separately in acetonitrile. Composite powders were then prepared in the second milling stage with hexane as process control agent and in the four possible combinations of one, both, or neither starting material being premilled in acetonitrile. Composites were characterized for morphology, size distribution, surface area, and reactive properties at low heating rates (thermal analysis) and high heating rates (ignition). Whether or not CuO was premilled, dense composites formed without premilling of Al. If Al was premilled in acetonitrile, however, loose agglomerates of refined Al and CuO particles formed in the second milling stage. Premilling changed the low-temperature reactions leading to ignition in the 8Al·3CuO thermites. These changes are attributed to increased porosity of the formed composites if aluminum is premilled with acetonitrile. It is shown that greater refinement and lower ignition temperatures are achievable using two-stage milling. [ABSTRACT FROM AUTHOR]

The influence of different milling conditions obtained using two high-energy mills on hydrogen desorption from MgH 2 -WO 3 composites was investigated. The morphology, particle and crystallite size were studied as a function of milling speed, vial's volume, and ball-to-powder ratio. The vial's fill level, the number, and type of milling balls and additive's content kept constant. Changes in morphology and microstructure were correlated to desorption properties of materials. Higher milling speed reduced particle size but, there is no significant crystallite size reduction. On the other hand, additive distribution is similar regardless of the energy input. It has been noticed that different energy input on milling blend, which is the result of combined effects of above-mentioned factors, reflects on desorption temperature but not on the kinetics of desorption. In fact, desorption mechanism changes from 2D to 3D growth with constant nucleation rate, despite obtained changes in microstructure or chemical composition of the material. • The effect of different milling conditions on H 2 desorption from MgH 2 -WO 3 is studied. • The increase of number of grain boundaries plays a decisive role in H 2 desorption. • H 2 sorption is rather governed by the crystallites size than particle size. • Energy input affects on desorption temperature but not on the kinetics of desorption. • Desorption kinetics changes from 2D to 3D growth with constant nucleation rate. [ABSTRACT FROM AUTHOR]

An investigation was carried out to evaluate the isothermal oxidation behavior of nickel based superalloys at 1100 °C for 120 h. The alloys which were microstructured and nanostructured were developed by spark plasma sintering system. The oxidation test was carried out at a temperature of 1100 °C in air at different exposure time up to 120 h. The nanostructured nickel based alloy possessed better oxidation resistance with the formation of continuous adherent alumina, chromia scales, and spinel on the alloy surface and with no significant internal oxides. The oxidation rate of NiO was observed to be lower in the nanostructured nickel superalloy due to low diffusion rate of Nickel. The oxidation kinetics followed a parabolic oxidation law. [ABSTRACT FROM AUTHOR]

Nanostructuring and catalyzing are effective methods for improving the hydrogen storage properties of MgH 2. In this work, transition-metal-carbides (TiC, ZrC and WC) are introduced into Mg–Ni alloy to enhance its hydrogen storage performance. 5 wt% transition-metal-carbide containing Mg 95 Ni 5 (atomic ratio) nanocomposites are prepared by mechanical milling pretreatment followed by hydriding combustion synthesis and mechanical milling process, and the synergetic enhancement effects of Mg 2 NiH 4 and transition-metal-carbides are investigated systematically. Due to the inductive effect of Mg 2 NiH 4 and charge transfer effect between Mg/MgH 2 and transition-metal-carbides, Mg 95 Ni 5 -5 wt.% transition-metal-carbide samples all exhibit excellent hydrogen storage kinetic at moderate temperature and start to release hydrogen around 216 °C. Among them, 2.5 wt% H 2 (220 °C) and 4.7 wt% H 2 (250 °C) can be released from the Mg 95 Ni 5 -5 wt.% TiC sample within 1800 s. The unique mosaic structure endows the Mg 95 Ni 5 -5 wt.% TiC with excellent structural stability, thus can reach 95% of saturated hydrogen capacity within 120 s even after 10 cycles of de-/hydrogenation at 275 °C. And the probable synergistic enhancement mechanism for hydrogenation and dehydrogenation is proposed. Image 1 • TiC, ZrC, WC were employed to improve the hydrogen storage properties of Mg 95 Ni 5. • Charge transfer effect between Mg/MgH 2 and TMCs facilitates the dehydrogenation. • Synergetic effects of Mg 2 NiH 4 and TMCs were investigated in depth. • HCS + MM-Mg 95 Ni 5 -5 wt.% TiC composite exhibits excellent cycle stability. [ABSTRACT FROM AUTHOR]

In this work, nanocrystalline tungsten oxide (WO 3) powder was obtained by high energy ball milling (HEBM) followed by heat treatment of tungsten (W) powder. HEBM significantly influenced the oxidation behavior by reducing the crystallite size and inducing lattice strain in W powder. The resultant nanocrystalline WO 3 shows variation in the optical bandgap with respect to the bulk counterparts. The alteration in the bandgap of WO 3 is ascribed to the changes in crystallite size and the unit cell volume. In the end, a thorough correlation between fundamental interactions of these changes was succinctly highlighted. Image, graphical abstract [ABSTRACT FROM AUTHOR]

One of the main challenges in the exploitation of nanomaterials is their production at low cost. Mechanical milling is an alternative for the production of nanomaterials, such as graphene. In this work we have studied the effect of different solvents (methanol, ethanol, acetone, hexane, toluene and xylene) on the production of graphene by attrition milling of graphite. Among the solvents tested, methanol showed to be able to produce graphene sheets more efficiently. Computer modeling suggests that although methanol and acetone have a weaker interaction with graphene (3.95 and 7.41 kcal/mol, respectively) compared to xylene (12.73 kcal/mol), they have a higher Gibbs free energy (6.46, 3.81 and 0.33 kcal/mol for methanol, acetone and xylene, respectively), suggesting a higher mobility on its surface, thus facilitating the exfoliation of graphene. The production of graphene was corroborated by Raman spectroscopy and transmission electron microscopy, showing to be a few layers graphene (<5 layers), approximately 1–6 μm in length, with a high degree of graphitization. Additionally, we also show that through this route is feasible to produce a few-layer graphene using synthetic and amorphous graphite as more economical alternatives. [ABSTRACT FROM AUTHOR]

Mechanical milling is a classic and well-known technique for altering the morphology and microstructure and hence the physical and chemical properties of metallic and ceramic materials. Herein we demonstrate that by using zirconia jars and balls as the grinding media, an optimum milling duration can significantly enhance the reactivity of light-burned magnesia, one of the most widely used materials at the industrial scale. For the milling durations of 0–24 h, the samples milled for 8 h exhibit an improvement in reactivity by nearly twofold due to a decrease in the particle size from micron to submicron/nanometer range and a significant increase in the lattice distortion and surface area. Milling for more prolonged durations causes severe microstructural deterioration and hence a reduction in the reactivity of light-burned magnesia. Since the high reactivity of light-burned magnesia is the key parameter for its diverse industrial applications, enhancing its reactivity by nearly two times through a simple process like mechanical milling can have a profound improvement in the production efficiency of various commercial products. [ABSTRACT FROM AUTHOR]

A novel, homogeneous, nanostructured and equiatomic (TiZrHfVNb)C 5 High Entropy Carbide (HEC) was successfully synthesised in a powder form by a mechanosynthesis process from the elemental mixture. This synthesis method for HECs, not previously reported, is simple, reproducible and carried out at room temperature. During milling, the transition metals (Ti, Zr, Hf, V and Nb) alloying and the diffusion of carbon (introduced as graphite) into the alloy structure are simultaneously induced, obtaining the expected (TiZrHfVNb)C 5 HEC. The room temperature method employed contrasts with those reported in the bibliography from binary carbides that are carried out at a very high temperature (1800–2200 °C), with the consequent energy savings. [ABSTRACT FROM AUTHOR]

Magnesium-based biomaterials have recently gained great attention as promising candidates for the new generation of biodegradable implants. This study investigated the mechanical performance and biodegradation behaviour of magnesium-zinc/hydroxyapatite (Mg–Zn/HA) composites fabricated by different powder mixing techniques. A single step mixing process involved mechanical alloying or mechanical milling techniques, while double step processing involved a combination of both mechanical alloying and mechanical milling. Optimum mechanical properties of the composite were observed when the powders were prepared using single step processing via mechanical alloying technique. However, Mg–Zn/HA composite fabricated through single step processing via mechanical milling technique was found to have the most desirable low degradation rate coupled with highest bioactivity. The composite achieved the lowest degradation rate of 0.039 × 10−3 mm/year as measured by immersion test and 0.0230 mm/year as measured by electrochemical polarization. Ca:P ratio of the composite also slightly more than enough to aid the initial bone mineralization, that is 1:1.76, as the required Ca:P ratio for initial bone mineralization is between 1:1 and 1:1.67. [ABSTRACT FROM AUTHOR]

For improving electrochemical performances of Mg-Ni-based alloys at ambient temperature, a portion of Mg was succeeded by Ce and the surface modification treatment was conducted by mechanical coating Ni. The nanocrystalline and amorphous Mg 1- x Ce x Ni 0.9 Al 0.1 (x = 0, 0.02, 0.04, 0.06, 0.08) + 50 wt%Ni metals were prepared. Impacts of Ce content and milling duration on the structure and electrochemical hydrogen storage properties have been researched. The results exposed that, the as-milled alloys can absorbing/desorbing hydrogen electrochemically very well at ambient temperature. Activation is not necessary as the first cycle can reach the maximal discharge capacity. Through 5 and 20 h milling, the maximum discharge capacities of alloys are 378.8 and 545.3 mAh/g, respectively. Cycling stability improves with Ce content and milling time growing. Specifically speaking, the retention rate of capacity at 100th cycle (S 100 = C 100 / C max) ascends from 36% to 66% for 5 h milled alloy and from 48% to 76% for 20 h milled alloy with Ce content growing from 0 to 0.08. Furthermore, many indexes such as electrochemical impedance spectrum, potentiodynamic polarization curves, high rate discharge ability, potential-step measurements, etc. proved that varying Ce content makes the alloys get their best electrochemical kinetic property. • Mg 1- x Ce x Ni 0.9 Al 0.1 (x = 0–0.08) + 50 wt%Ni alloys were prepared by ball milling. • Effects of different milling time and Ce content were investigated. • A Ni coating layer was formed on the surface of alloy particles. • Changing Ce content makes the alloys reach their best electrochemical kinetics. [ABSTRACT FROM AUTHOR]

Structural investigations showed that the crystal structure influences the hydrogen storage properties of MgH 2. The crystal structure and dehydriding temperature of MgH 2 activated by high energy ball milling under an argon atmosphere were studied. The X-ray diffraction characterization showed that a small amount of tetragonal α-MgH 2 phase transforms into crystalline γ-MgH 2 of an orthorhombic structure during milling, and γ-MgH 2 peak intensity increased with increasing ball milling time within a certain limit, but disappeared early in the hydrogenation cycle at a temperature of 300 °C. We studied the phase structure and the stability of the MgH 2 during absorption/desorption cycles as well as thermal stability in a context of sustainable use of MgH 2. • γ-MgH 2 phase has a lower temperature of hydrogen desorption than β-MgH 2 phase. • The disappearance of the γ-MgH 2 phase was found to be temperature dependent. • Working at a temperature of 250 °C can stabilize the γ-MgH 2 phase. • Milling decreases particle size but cycling and heating cause agglomeration. [ABSTRACT FROM AUTHOR]

In this work, the mechanical milling of a FeTiMn alloy for hydrogen storage purposes was performed in an industrial milling device. The TiFe hydride is interesting from the technological standpoint because of the abundance and the low cost of its constituent elements Ti and Fe, as well as its high volumetric hydrogen capacity. However, TiFe is difficult to activate, usually requiring a thermal treatment above 400 °C. A TiFeMn alloy milled for just 10 min in a 100 L industrial milling device showed excellent hydrogen storage properties without any thermal treatment. The as-milled TiFeMn alloy did not need any activation procedure and showed fast kinetic behavior and good cycling stability. Microstructural and morphological characterization of the as-received and as-milled TiFeMn alloys revealed that the material presents reduced particle and crystallite sizes, even after such short time of milling. The refined microstructure of the as-milled TiFeMn is deemed to account for the improved hydrogen absorption-desorption properties. • First industrial-sized milling treatment procedure for TiFe alloys reported. • Milled alloy does not need thermal activation. • Milled alloy shows superior H 2 sorption behavior vs. thermally treated alloy. • Procedure is easily scalable to larger mills. [ABSTRACT FROM AUTHOR]