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Al-rich alloys prepared by milling and melting were characterized by a range of instrumental analysis techniques and employed for hydrolytic hydrogen production. The hydrolysis reaction of each Al-rich alloy with water was measured. The hydrolysis properties of Al-rich alloys prepared by milling method were superior to those prepared by melting method with same composition. In particular, the Al-5wt%Ga-3wt%In-5wt%Sn alloy prepared by milling featured better hydrolysis properties than that obtained by melting, achieving a hydrogen yield of 1146.0 mL g−1 and a maximum hydrogen generation rate of 840.0 mL min−1 g−1 in tap water within 10 min at 25 °C and atmospheric pressure. Moreover, the phase compositions, chemical states, elemental distributions, and thermal behaviors of melting and milling samples were investigated, and the activation mechanism was discussed as well. • Al-rich alloy prepared by milling method exhibits superior hydrolysis properties. • The hydrogen yield and reaction time could be expressed as a piecewise function. • No XRD peaks of Ga may be ascribed to the melting of Ga (melting point = 29.8 °C). • In, Sn, and Ga in the milling 535 aggregated along Al crystal boundaries. • The morphologies of melting and milling 535 were preparation method-dependent. [ABSTRACT FROM AUTHOR]

Abstract For the aim of thermal barrier application in vehicle engines, a specific FeCrNbBSiC cored wire of consideration was produced to fabricate amorphous coating by wire-arc spraying. The microstructure and thermal conductivity of the as-deposited coating were characterized in detail. The results show that the FeCrNbBSiC coating (FB coating) primarily consists of amorphous phase owing to the combination of proper composition design and rapid quenching of wire-arc spraying. However, a fraction of crystalline phases coexists with the amorphous matrix, due to the both effects of partially incomplete alloying and continuous annealing. Depending on the expected amorphous structure, thermal conductivity of the developed FB coating is as low as 2.15 W/mK at room temperature, almost half of the referenced 316L stainless steel coating (SS coating, 4.20 W/mK), and displays relatively slow and limited increase with elevated temperature up to 500 °C. By means of temperature distribution analysis, an obviously higher temperature is found on the top surface of FB coating covered piston, which implies a benefit of enhancing heat energy conversion. Simultaneously, the temperature of aluminium alloy substrate could also be reduced by covered coating as the role of thermal insulation. Therefore, the wire-arc sprayed FeCrNbBSiC amorphous coating developed here with excellent thermal barrier performance and economic advantage could be a promising innovation and candidate for metal-based thermal barrier coatings applied in vehicle engines. Highlights • Innovative scheme of metal-based thermal barrier coatings was designed. • Wire-arc sprayed FeCrNbBSiC amorphous coating with high T x was obtained. • Incomplete alloying and continuous annealing result in crystalline phases formed. • Amorphization endows excellent thermal barrier ability for this coating (κ = 2.15 W/mK). • Application of this coating improves power efficiency and protects substrate effectively. [ABSTRACT FROM AUTHOR]

Amongst the structural materials for high temperature applications that are currently in the focus of research, high entropy alloys (HEAs) exhibit very promising features, such as high strength, good fracture toughness, high temperature phase stabilities and excellent resistance against softening at elevated temperatures. Key influencing factors for high temperature applications are the mechanical properties at elevated temperatures as well as the oxidation behavior of a given material. Al x CrFeCoNi alloys have been mostly investigated among different HEAs. However, up to now there are limited reports dealing with the oxidation behavior of Al x CrFeCoNi–based HEAs, especially with respect to the effect of Si-alloying on the oxidation behavior at elevated temperatures. In this study, the oxidation behavior of two HEAs, Al 0.6 CrFeCoNi and Al 0.6 CrFeCoNiSi 0.3 , were comparatively investigated at T = 800 °C, 900 °C and 1000 °C in air to determine the effect of Si-alloying. The results show that oxidized layers typically consist of Cr 2 O 3 /spinel and Al 2 O 3 with an underlying Al-depleted zone. AlN was found inside the Al-depleted zone with the exception of Al 0.6 CrFeCoNiSi 0.3 oxidation at T = 800 °C. However, Si alloying only positively influenced the oxidation behavior at T = 800 °C. Here, it promoted the formation of a continuous Al 2 O 3 layer. The Si-alloying did not enhance the oxidation resistance at T = 900 °C and 1000 °C. [ABSTRACT FROM AUTHOR]

It is believed that the construction of a well-hybridized and nanoscale SnS 2 -rGO interconnection would make Li+ diffusion distance shorter, cycle performance stable and high-rate property remarkable application in the LIBs anodes. Here, a novel SnS 2 /rGO aerogel with ultrathin SnS 2 nanosheets, well-hybridized networks, and desirable covalent-bonded interconnection was successfully prepared by a modified one-step hydrothermal method. The aerogels were used for anode of lithium-ion batteries (LIB), and exhibited a remarkable electrochemical performance, including an ultra-high initial specific capacity (1682 mAh g−1), excellent rate performance (474 mAh g−1 at the rate of 10 A g−1), and perfect cycle stability (1388.4 mAh g−1 after 100 cycles at 0.1 A g−1), superior to those of previous reports. It is obvious that the aerogel's well-hybridized and covalent-bonded networks, super stable and intact structure, and improved electron conductivity would play a very important role during charging/discharging of the improved Li+ transportation. Therefore, the SnS 2 /rGO aerogel materials created by us would be a very promising candidate for future advanced lithium-storage-type power sources. • Well-hybridizing SnS 2 /rGO aerogels were prepared via a modified hydrothermal method. • Desired rGO networks were well-bonded with interconnected ultrathin SnS 2 nanosheets. • SnS 2 /rGO hybrids for LIB's anodes exhibit highly specific capacity of 1682 mAh·g−1. • SnS 2 /rGO anodes maintained capacity of 1388.4 mAh·g−1 at 0.1 A g−1 after 100 cycles. • SnS 2 /rGO anodes also showed excellent rate property of 474 mAh·g−1 at high 10 A g−1. [ABSTRACT FROM AUTHOR]

Highlights: [•] Mechanochemical route is efficient to prepare NiO nanoparticles. [•] Thermodynamic in the formation procedure is carefully investigated. [•] Size of the NiO nanoparticles can be easily controlled by changing heat temperature. [Copyright &y& Elsevier]

Si-rich Mo-Si-B powders (Mo-62Si-5B at%) were deposited on Nb-Si based alloy by laser cladding assisted with ultrasonic vibration. The obtained coatings mainly consist of MoSi 2 and (Mo, X) 5 Si 3 (X = Nb and Ti). With the introduction of ultrasonic vibration during laser cladding, the lath-shaped MoSi 2 phase transforms into cellular gradually. Meanwhile, the discrepancy on the microstructure of the top region and the bottom region is eliminated gradually, indicating that the cavitation and acoustic streaming of ultrasonic vibration not only refines the microstructure, but also homogenizes the element and phase distribution in the coatings. High-temperature oxidation experiment at 1250 ℃ were conducted to assess the oxidation resistance of the coatings. Compared with Nb-Si alloy, the coated specimens have much lower oxidation weight increase. Furthermore, with the assistance of ultrasonic vibration, the oxidation resistance of the coating is enhanced further. The oxide scales on the coatings consist of two layers: an upper amorphous aluminoborosilica with TiO 2 particles dispersed and a lower crystalline SiO 2 layer. With the introduction of ultrasonic vibration, the microstructure of the coatings is refined, resulting in more phase and grain boundaries in the coatings. Therefore, the diffusion of the elements to the surface is accelerated and the protective oxide scale can be formed quickly. • Si-rich Mo-Si-B coatings were prepared on Nb-Si based alloy by laser cladding assisted with ultrasonic vibration. • The ultrasonic vibration refines the microstructure and homogenizes the phase distribution in the coatings. • The oxide scale on the coatings consists of an upper amorphous aluminoborosilica and a lower crystalline SiO 2 layer. • The ultrasonic vibration improves the oxidation resistance of the coatings because of more phase and grain boundaries. [ABSTRACT FROM AUTHOR]

Abstract Cu-10Sn alloy with body-center-cubic (BCC) lattice structure was fabricated through selective laser melting (SLM). The geometry of SLMed BCC lattice Cu-10Sn alloy (rod diammeter ∼300 μm, length ∼700 μm) was in good agreement with the design model. Similar with the nearly full density Cu-10Sn alloy, columnar also constituted the majority parts of the lattice structure Cu-10Sn, but exhibited various morphologies due to the different grain growth orientation under thermal effect. The gowth orientation of columnar grain in the rods oriented to the as-fabricated layer due to the higher thermal conductivity of the as-fabricated layers. Graphical abstract Image 1 Highlights • Cu-10Sn alloy with BCC lattice structure was fabricated through SLM. • The geometry of BCC lattice Cu-10Sn alloy was in good agreement with the design model. • The BCC lattice Cu-10Sn exhibited various grain morphologies under thermal effect. • The gowth orientation of columnar grain in the rods oriented to the as-fabricated layer. [ABSTRACT FROM AUTHOR]

A multiple grain size distributed Al-based composite was fabricated through ball milling the amorphous powder mixed with pure Al powder followed by spark plasma sintering. The composite consisted of amorphous/nanocrystalline, submicron grain and micron grain, exhibiting outstanding mechanical properties. The superior strengthen effect of the amorphous/nanocrystalline region contributed to the exhibiting specific strength (5.66 × 10 5 Nm/kg) of the composite. The orderly plastic deformation occurred within FCC-Al micron grain region and submicron grain region during compression. And the progressive deformation restrained the strain localization and unstable propagation of the crack, leading to the plastic deformation (4.3%) of the composite. [ABSTRACT FROM AUTHOR]

W-based composites with the different immiscible second phases (Cu and Cu10Sn) were prepared by laser powder bed fusion (LPBF). The immiscible W phase and Cu/α-Cu phases were prone to separate during LPBF. The melted W phase could easily fuse together and form W matrix, and Cu or α-Cu phase distributed within the gaps among W phase. Cu or α-Cu phase can provide a gradient cooling way for the solidification of W phase through the transformation of 'solid-liquid-gas' during LPBF. The evaporation of Cu or Sn accelerated the heat dissipation, which caused the grain refinement of W. Higher thermal conductivity of Cu than α-Cu leads to the relative finer grain size of W phase in W-Cu composite. The heat conduction direction between W phase and Cu/α-Cu also affected the grain morphology. Heat continued transferred from W to Cu/α-Cu induced the columnar grain growth of W, the interlacing distribution of W and Cu/α-Cu made the growth of W columnar grains radiate out from the center Cu/α-Cu phase. Remarkable, cracks were severely restrained in W phase simultaneously although W phase melted completely. This is not only related to improvement of strength and ductility of W caused by grain refinement, but also because of the interlacing distribution of W and Cu/α-Cu phases, which could effectively reduce the stress degree in W phase during LBPF. [Display omitted] • W-Cu and W-Cu10Sn composites with free crack were successfully prepared by LPBF. • W phase formed skeleton structure in both W-Cu and W-Cu10Sn composites. • The addition of Cu/ Cu10Sn induced the grain refinement of W phase. [ABSTRACT FROM AUTHOR]

• Mo-10Si-(0, 5, 10, 15)B (at.%) alloys were prepared by vacuum arc-melting technique. • The effect of B content on phase constitution was discussed and the microstructure evolution was illustrated. • The relationship between the microstructure of the alloys and the mechanical properties was established. • The oxidation resistance of the alloys was evaluated and the mechanism of oxidation resistance was studied. The Mo-10Si-(0, 5, 10, 15)B (at.%) alloys located in Mo ss (Mo solid solution) +Mo 3 Si +T2 (Mo 5 SiB 2) region were prepared by arc melting. The effect of B content on the microstructure, microhardness, fracture toughness and oxidation resistance of the alloys was studied. In the Mo-10Si alloy, there are primary Mo ss and peritectic Mo 3 Si phases. With the addition of B, (Mo ss + T2) binary and (Mo ss + T2 + Mo 3 Si) ternary eutectics emerge in Mo-10Si-(5, 10)B alloys. For Mo-10Si-15B alloy, primary Mo ss disappears and the microstructure is only composed of binary and ternary eutectics. With the increase of B content, the proportion and grain size of Mo ss decrease. The microhardness of alloys increases with the increase of B content due to the increasing intermetallics. The fracture toughness of alloys decreases obviously in single-edge notched three-point bending testing (SENB) and the fracture mode transforms from transgranular fracture to intergranular fracture because of the refinement of Mo ss. In the high-temperature oxidation test at 1250 °C, the oxidation weight loss of the alloys decreases with the addition of B due to the densification of the borosilicate layer. [ABSTRACT FROM AUTHOR]

This study systematically investigates the effect of oxygen on the microstructural evolution as well as the macro/micromechanical characterization of Ag sinter paste during the aging process at 250 °C for 1000 h. The sintered Ag joint is separated into two groups and, respectively, kept in air and vacuum (10−4 Pa) atmospheres. The microstructure of sintered Ag paste become clearly coarsened after aging at 250 °C in air for 100 h, while it remains almost the same as in the initial state in vacuum, even after aging for 1000 h. The different microstructural evolutions are investigated in detail by transmission electron microscopy, which reveals that coarsening are involved in the Ag-O reaction and form a large number of Ag nanoparticles around sintered Ag particles, as well as enhance coalescence. Furthermore, the macro/micromechanical properties of sintered Ag paste, after aging in air and vacuum atmospheres, are evaluated by a die shear test and a nano-indenter system with a spherical diamond tip. Shear strength and fracture mode were systematically analyzed. The micromechanical properties of sintered Ag paste, including Young's modulus and hardness, depend on its microstructure and are largely influenced by its porosity, which decreases from initiation to 250 h and recovers after aging for 500 h in air. However, there is almost no change during the aging process in the vacuum atmosphere. The results of this study contribute to a better understanding of the microstructural evolution and the mechanical properties of sintered Ag joints, including the change in bonding quality and Young's modulus during aging for actual power modules, which are packaged by a resin. Image 1 • Oxygen effect on the microstructural evolution and mechanical properties of Ag sinter paste were investigated. • Microstructure of Ag sinter paste become coarsening in air aging but almost not any change in vacuum aging. • Coarsening behaviors maybe mainly caused by Ag-O reaction but not the self-diffusion kinetics of Ag atoms. • In-suit formation of Ag nanoparticles played a crucial role in the coarsening behaviors of Ag sinter paste. • Micromechanical properties of Ag sinter paste depend on its microstructure and influence by aging atmosphere. [ABSTRACT FROM AUTHOR]

Almost fully dense AlCrFeNiV HEA consisting of face-centred-cubic (FCC) solid solution and L1 2 nano phase was prepared from gas-atomized alloy powder with optimized selective laser melting (SLM) processing parameters. Microstructure characterization reveals the presence of hierarchical structures including columnar grains, sub-grains, L1 2 nano phase and dislocations in SLMed HEA. Unique columnar grains ranging from several tens of microns up to 200 μm grow along the direction of the temperature gradient. High cooling speed and non-equilibrium solidification during SLM process induced the formation of sub-grains in every columnar grain, accompanied with the heterogeneous distribution of dislocations and L1 2 nano phase. The SLMed AlCrFeNiV HEA exhibited an outstanding combination of high strength (ultimate tensile strength ∼1057.47 MPa) and excellent ductility (plastic strain ∼30.3%). The characteristic hierarchically heterogeneous structure contributes to the increase of strength without losing ductility. The sub-grains contribute significantly to the enhanced strength through dislocation hardening. The excellent ductility is correlated with the progressive work-hardening mechanism regulated by the heterogeneous distribution dislocation and L1 2 nano phase within sub-grains. Image 1 • Almost fully dense AlCrFeNiV HEA was fabricated by SLM. • SLMed HEA consists of FCC phase and L1 2 nano phase. • SLMed HEA shows hierarchically heterogeneous microstructure. • SLMed HEA exhibits high ultimate tensile strength of 1057.47 MPa and plasticity of 30.3%. [ABSTRACT FROM AUTHOR]