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The Mo-12Si-8.5B alloy was surface-remelted by laser and electron beam, and the microstructure of its melt pool and substrate regions were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy spectrometry (EDS) techniques. It was found that the composition of the surface phases in the Mo-12Si-8.5B alloy did not change by the high-energy beam surface remelting process, but the microstructure of the molten pool region was significantly different from that of the substrate region, and its phase distribution was more uniform. Dendrites appeared on the surface of the material under the action of both processes, and the Si- and B-rich phases were mainly gathered in the interdendritic region. In the melt pool of the laser-remelted specimens, the α-Mo phase was continuously distributed with an average dendrite length of 70 µm, while the α-Mo phase distribution in the melt pool of the electron beam remelted specimens were relatively concentrated, with a larger dendrite size and an average dendrite length of 120 µm. The dendrite size in the melt pool of the laser remelted material was smaller, and the distribution of the elements was relatively uniform. Using a laser beam as the heat source was more favorable for the next step of the additive manufacturing of the core parts of hypersonic vehicles. [ABSTRACT FROM AUTHOR]

The purpose of this work is to optimize the penetration temperature to obtain 316 L honeycomb-filled tube/aluminum matrix composite (HFT/AMC) with good wear resistance. Utilized selective laser melting technology to fabricate honeycomb-filled tubes as reinforcement for the composite material. HFT/AMC was prepared by filling aluminum into honeycomb-filled tubes under three different temperatures of 800 °C, 850 °C, and 900 °C through vacuum infiltration casting. And performed tissue characterization and performance testing. Microstructure, hardness, XRD, and EDS studies showed that the composite materials generate intermetallic compound transition layers of over 100 μm, and the overall strength of the interface was improved. A large number of intermetallic compounds and honeycomb-filled tubes distributed in the aluminum matrix inside the cells jointly strengthen the aluminum-based material. Inspection of worn surfaces of HFT/AMCs revealed abrasive and oxidative wear as the main wear mechanisms. Considering the wear of the produced HFT/AMC under certain conditions, the most suitable infiltration temperature is 850 °C (wear rate: 0.52 ± 0.16 [(mm3/N·m) × 10−3]). This study confirmed that honeycomb-filled tubes can significantly improve the tribological properties of aluminum-based materials. [Display omitted] • HFT/AMCs at different temperatures can achieve good metallurgical bonding. • The IMC layer of HFT/AMC at different temperatures exceeds 100 μm. • The Al matrix hardness of HFT/AMCs at different temperatures is enhanced. • HFT/AMC at different temperatures have excellent tribological properties. • HFT/AMC-stabilized CoF has potential applications in the field of friction materials. [ABSTRACT FROM AUTHOR]

Interface between lattice reinforcement and matrix played a key factor on properties of the lattice reinforced aluminum matrix composites. However, the effect of interface composed of intermetallic compounds on the properties of 316 L lattice/Al composites was still unclear. In this study, 316 L lattice reinforced aluminum composite with continuous interface were prepared by combining laser powder bed fusion (LPBF) and vacuum infiltration, and effect of infiltration temperature on interface evolution and properties of the composite was investigated. Results indicated that a continuous dual-phase interfacial layer consisting of hard intermetallic compounds η-Fe 2 Al 5 and θ-FeAl 3 was formed between the reinforcement and matrix due to diffusion and reaction of iron and aluminum atoms, and the size of needle-type FeAl 3 phase in the interfacial zone increased when infiltration temperature was up from 800 °C to 900 °C. It also confirmed that reinforced by 316 L lattice and hard intermetallic compounds layer, the composite showed excellent mechanical and wear resistant properties, with compressive strength of 657 ± 32 MPa and specific wear rate of 0.20 × 10−3 (mm3/N·m) for the sample prepared at 800 °C, which were over 10 times and one fifth of that of the aluminum matrix individually. This study provides a new strategy for developing 316 L lattice/Al composites with excellent properties. [Display omitted] • LPBF and infiltration are adopted to prepare 316 L lattice/Al composites. • The interface is mainly composed of η-Fe 2 Al 5 and θ-FeAl 3 intermetallic compounds. • High-strength interface greatly contributed to high compressive strength. • Composites show five times increase in the wear resistance of aluminum. [ABSTRACT FROM AUTHOR]

Microstructures dominate the physical properties of fractal porous media, which means the clarification of complexity types and their assembly are of fundamental importance for static or dynamic purposes. In this work, we identified fractal porous media to dual-complexity systems composed of stationary and scale-invariant complexities as per fractal topography theory, and proposed an open mathematical framework to characterize complexity assembly in microstructures, realized the original complexity, such as random, multi-phase, and multi-type features by the quartet structure generation set (QSGS) algorithm, and unified the behavioral complexity, including the self-similar and self-affine properties by fractal topography model. For demonstration, the control mechanisms on the microstructures from different complexities are discussed, with their physical implications and relations to the physical properties of porous media clarified in principle. The results indicate that our framework is open to arbitrary original and behavioral complexities, and eases the modeling of multi-scale microstructures and the property estimation significantly. [ABSTRACT FROM AUTHOR]

YAG ceramic was brazed to Kovar alloy under a high vacuum of 6–8 × 10−4 Pa. A good contact angle (θ eq = 10.7°) was obtained by wetting AgCuTi filler metal on the YAG ceramic substrate, and the associated interfacial microstructure was characterized. The microstructure of the achieved YAG/Kovar joints brazed by AgCuTi filler was characterized by SEM, TEM and XRD, which was found to be YAG/Y 2 O 3 /(Fe, Ni)Ti/Ag(s, s) + Cu(s, s)/Fe 2 Ti + Ni 3 Ti/Fe 2 Ti/Kovar. The effects of different brazing temperatures on the joint structure were investigated. The thickness of the (Fe, Ni)Ti reaction layer increases, and the banded structure formed by Fe 2 Ti and Ni 3 Ti intermetallic compounds (IMCs) widens with increasing brazing temperature. Nanoindentation and shear tests were used to characterized the mechanical properties of the joints. As the brazing temperature increased, the shear strength of the joints first increased and then decreased. A joint with an optimal shear strength of 51.3 MPa was obtained at 870 °C for 10 min. The nanoindentation test reveals the obvious differences in mechanical properties between phases: (Fe,Ni)Ti phase has higher Young's modulus and hardness than Fe 2 Ti–Ni 3 Ti phase and Ag–Cu eutectic. • YAG and Kovar was brazed with AgCuTi filler metal. • Typical microstructure: YAG/Y 2 O 3 /(Fe,Ni)Ti/Ag(s,s), Cu(s,s)/Fe 2 Ti, Ni 3 Ti/Fe 2 Ti/Kovar. • A contact angle of 10.7° was obtained by wetting AgCuTi filler metal on YAG. • Mechanical properites of the joint were confirmed by nanoindentation and shear strength. • The maximum shear strength of 57.3 MPa was achieved with the parameter of 870 °C/10 min. [ABSTRACT FROM AUTHOR]

The coarse segregative eutectic phases, emerged in the twin roll casting (TRC) process of Mg strips, which cannot be resolved solely by controlling the processing variables or post heat treatment, are detrimental to the subsequent rolling deformation. Considering it, we introduce the pre-rolling steps on the TRC Mg-4Al-2Sn-1Zn (ATZ421) alloys, which is expected to facilitate the dissolution of these segregative phases by increasing distortion of crystal lattices and rolling stress, and further investigate the effect of a single pass or two passes pre-rolling on the microstructure evolution and tensile properties. It indicates that the pre-rolled alloy with two passes presents more uniform precipitates and higher twinning density in comparison with that using a single pass. The uniform distribution of precipitates in two passes pre-rolling is due to the increase in density of dislocations and deformed twins, which results in more distortion of crystal lattices with more stored energy, facilitating the diffusion of solutes. Moreover, the pre-rolling of two passes introduces more rolling stress into Mg matrix, which is beneficial for the crush of coarse eutectic phases, and further accelerates the sufficient dissolution of second phases. After the subsequent rolling and annealing processes, the sheet with pre-rolling deformation of two passes shows finer microstructure, which mainly benefits from the pinning effects of uniform nano-sized precipitates. As a result, the annealed sheet with two-pass pre-rolling deformation exhibits an advantageous combination of high strength and high ductility with fine microstructure, showing an ultimate tensile strength of ~297 MPa, a yield strength of ~ 205 MPa and an elongation of 25.0%. This work provides an effective method of dissolving the coarse segregative phases in the TRC Mg alloys with significant potential for industrial production. [ABSTRACT FROM AUTHOR]

The advantage of electronegativity of nitrogen has been utilized to improve the mechanical properties of thin film metallic glasses (TFMGs) by forming nanoclusters in the amorphous matrix. Despite the high electronegativity of fluorine, it has not been used as doping for TFMGs because of the toxicity of fluorine gas. In this work, we controlled the flow rate of the nontoxic SF 6 during reactive sputtering to form fluorine- and sulfur-doped Zr-Ti-Ni TFMGs, and the microstructure of nanoclusters embedded in the amorphous matrix was obtained to result in improved mechanical properties of TFMGs. In addition, the potential bindings and compounds were investigated using X-ray photoelectron spectroscopy. The binding energy shift in the spectra provided the evidence of interaction between Zr and F to form nanoclusters. [ABSTRACT FROM AUTHOR]

The effect of trace Ce addition on the microstructure evolution and corrosion behavior of dilute Mg-0.6Al-0.5Mn-0.25Ca-xCe (x = 0.1–0.3 wt%) alloys were investigated using immersion tests and electrochemical measurements. The Ce addition caused the formation of Al 8 Mn 4 Ce and Al 11 Ce 3 , which were less noble than Al 8 Mn 5. Strikingly, the alloy containing 0.3 wt% Ce exhibited the lowest average corrosion rate of 4.13 mm y−1, which was 6.5 times lower than that of Ce-free alloy. The outstanding anti-corrosion properties were attributed to the low potential difference between Ce-containing phases and matrix, the compact composite oxide film (MgO-CeO 2 -Al 2 O 3), and the enrichment of Fe in Ce-containing phases. [Display omitted] • Corrosion resistance of Mg-0.6Al-0.5Mn-0.25Ca alloy was improved by adding trace Ce. • The Al 8 Mn 4 Ce and Al 11 Ce 3 were formed instead of the nobler Al 8 Mn 5 in Ce-free alloy. • Dense composite oxide film (MgO-CeO 2 -Al 2 O 3) hindered the spread of corrosion. • The enrichment of Fe in Ce-containing phases weakened the harmful effect of impurity. • A new method was proposed to improve the corrosion resistance of dilute Mg alloys. [ABSTRACT FROM AUTHOR]

Formability is the key to restrict the widespread industrial application of Al–Cu–Li alloy. And low-temperature forming has been considered to be a promising material formation technique. This work investigates the origin of the simultaneous increase in strength and ductility that takes place in Al–Cu–Li alloys at low-temperature. We found that as the temperature decreased (ranging from 298 to 77 K), both the strengthening and ductility of Al–Cu–Li alloys with full annealing (O-state) and water quenching (W-state) increased simultaneously, producing a better strength-ductility synergy compared to room temperature. The dislocation slip is the primary deformation mechanism of two different state alloys at low-temperature and room temperature. The improved ductility at low-temperature results from the activated slip systems, promoted multisystem slip, prolonged elastic-plastic transition, and larger strain gradient, which induces the deformation to be more homogeneous. The improved strength is the result of dynamic recovery inhibition, which induces an increased dislocation density. This work indicates that Al–Cu–Li alloys have good ductility at low-temperatures and promise low-temperature applications. • Lower deformation temperature strategy to achieve an excellent combination of ductility and high strength in Al–Cu–Li alloys. • The dislocation density increases significantly and the interactions of dislocations between different slip systems hinder the further movement of dislocations at low-temperature. • The number of activated slip systems increases, the number of slip bands increases, and the deformation are more uniform at low-temperature. [ABSTRACT FROM AUTHOR]

The morphologies of ZnO with various microstructures synthesized by a facile solution-phase method using different molar ratios of zinc nitrate hexahydrate (Zn(NO 3 ) 2 ) to hexamethylenetetramine (HMTA) and trisodium citrate were investigated. It revealed that the molar ratio of Zn(NO 3 ) 2 to HMTA plays a significant role in the formation of hollow ZnO microstructures. Meanwhile ZnO with rod-like, flower-like or spherical-like microstructures can be nicely tailored by varying the molar ratio of Zn(NO 3 ) 2 to HMTA and trisodium citrate during growth process. In addition, the photocatalytic decolourization of aqueous solution of methyl orange in the presence of various morphological ZnO powder was investigated under ultraviolet light irradiation. The results showed that hollow ZnO microstructures had extremely high photocatalytic activities compared with those of solid ZnO samples. This remarkable photolytic activity is mainly due to their unique hollow structures, which resulting in larger surface area to volume ratio. [ABSTRACT FROM AUTHOR]

Plasmonic nanostructures display unique and strongly enhanced optical properties, therefore hold great promise for a wide range of spectroscopic applications, particularly surface-enhanced Raman spectroscopy (SERS). It is well acknowledged that the major contributions to SERS arise from molecules positioned in nanojunctions where the optical field is intensively concentrated due to localized surface plasmon excitations. One of the key challenges in SERS therefore lies in the design and fabrication of plasmonic nanostructures with controllable nanojunctions. In recent years, by exploiting the unparalleled base-pairing self-recognition properties, DNA-mediated assembly has emerged as a powerful and programmable tool for the accurate construction of complex and hierarchical plasmonic nanostructures with well-defined geometry and topology. In this review, we will summarize recent advances on design and fabrication of a rich variety of plasmonic nanostructures by virtue of DNA nanotechnology, and discuss their optical properties as well as applications in SERS. [ABSTRACT FROM AUTHOR]

Bone remodeling is an evolutionary process of microstructure configuration that occurs under a variety of external stimulations. Critical to the process are the osteoblast and osteoclast cells, which relate to bone formation and absorption. Unlike osteoclast cells, the osteoblast cells are sensitive to mechanical strain, which indicates that mechanical strain plays a key role in the bone remodeling process. In this paper, a modified governing equation for bone remodeling is proposed to simulate the remodeling process at a microscale. Equivalent strain was used as the stimulus, and the influence of medicine was taken into account. A forward Euler integration method and a strain distribution solver, Abaqus/standard, were used to solve the governing equation. Three sets of simulations were conducted based on the idealized microstructure configuration, the semi-idealized microstructure configuration (the space truss structure) and the actual bone microstructure configuration derived from a Micro-CT scan experiment. The results indicate that mechanical load eventually determines the microstructure configuration as bone structure attempts to support the mechanical load with minimal mass. The simulation confirms that Denosumab, which has been wildly used to treat osteoporosis, effectively increased bone density and decreased porosity. Furthermore, bone microstructure samples were obtained through the simulation to provide the elastic module – porosity data points. All of the simulations indicated that the proposed method was reasonable and effective. [ABSTRACT FROM AUTHOR]

One of important factors determining the lifetime of proton exchange membrane fuel cells (PEMFCs) is degradation and failure of membrane electrode assembly (MEA). The lack of effective mitigation methods is largely due to the currently limited understanding of the degradation mechanisms for fuel cell MEAs. This study adopted the accelerating degradation technique to analyze durability of MEA using drive cycle test protocol developed by Chinese NERC Fuel Cell & Hydrogen Technology to assess the long-term durability of fuel cells for vehicular application. During 900 h durability test of the MEA, the polarization curve, cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) were performed as diagnostics during and on completion the test. The experimental results show that the performance degradation rate of the cell is about 70 μV h −1 at the operating current density of 500 mA cm −2 , failure of the proton exchange membrane is the decisive factor leading to the failure of the MEA. And the damage of the micro-structural of catalytic layer, crucial for electrochemical reaction, is the decisive factor for the performance degradation. [ABSTRACT FROM AUTHOR]

Objective: To detect and compare the bone microstructure and osteoblast and osteoclast activity in different regions of human osteonecrotic femoral heads. Methods: Osteonecrotic femoral heads were obtained from 10 patients (6 males, 4 females; Ficat IV) undergoing total hip arthroplasty between 2011 and 2013. The samples were divided into subchondral bone, necrotic, sclerotic, and healthy regions based on micro-computed tomography (CT) images. The bone microstructure, micromechanics, and osteoblast and osteoclast activity were assessed using micro-CT, pathology, immunohistochemistry, nanoindentation, reverse transcription polymerase chain reaction (RT-PCR), tartrate-resistant acid phosphatase staining and Western blotting. Results: (1) The spatial structure of the bone trabeculae differed markedly in the various regions of the osteonecrotic femoral heads. (2) The elastic modulus and hardness of the bone trabeculae in the healthy and necrotic regions did not differ significantly (P >0.05). (3) The subchondral bone and necrotic region were positive on TRAP staining, while the other regions were negative. (4) On immunohistochemical staining, RANK and RANKL staining intensities were increased significantly in the subchondral bone and necrotic region compared with the healthy region, while RUNX2 and BMP2 staining intensities were increased significantly in the sclerotic region compared with the necrotic region. (5) OPG, RANK, RANKL, RUNX2, BMP2, and BMP7 protein levels were greater in the necrotic and sclerotic region than in subchondral bone and the healthy region. Conclusion: The micromechanical properties of bone trabeculae in the necrotic region did not differ significantly from the healthy region. During the progress of osteonecrosis, the bone structure changed markedly. Osteoclast activity increased in subchondral bone and the necrotic region while osteoblast activity increased in the sclerotic region. We speculate that the altered osteoblast and osteoclast activity leads to a reduction in macroscopic mechanical strength. [ABSTRACT FROM AUTHOR]

Abstract: Durability is one of the major barriers to proton exchange membrane fuel cells (PEMFCs) being accepted as a commercially viable product. It is therefore important to understand the degradation phenomena of MEA (membrane electrode assembly) in PEMFCs and analyze degradation mechanisms. This study adopted the accelerating degradation technique to analyze durability of PTFE/Nafion MEA using the Taiwan HS-150 fuel cell tester and MEA/Stack Durability Protocol developed by the Fuel Cell Technical Team (FCTT) of the FreedomCAR and Fuel Partnership. The experimental process for the MEA degradation contains dry/wet and load cycling. During durability test of the MEA, the polarization curve, cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) are used for diagnosing state of the MEA. The experimental results show that failure of the proton exchange membrane is the decisive factor leading to the end-of-life of the MEA and the electrochemical reaction micro-structural damage of catalytic layer is the decisive factor of the performance degradation and stability deteriorates. [Copyright &y& Elsevier]

• A Zn-containing alloy with improved crack tolerance and strength is exploited. • Trace Zn promotes pyramidal slips, inhibits twinning, and enhances GB cohesion. • Zn segregation enables crack buffering with a stepped interfacial transition zone. • In-situ TEM proves the emission of 〈 c + a 〉 dislocations despite microcracking. • Higher strength is mainly due to enhanced solid-solution strengthening. Effects of solute segregation at grain boundaries (GBs) on the deformation mechanism and fracture behavior remain obscure for magnesium (Mg) alloys. Here, by introducing Zn segregation at GBs, we obtained an Mg-0.5Al-0.4Mn-0.2Ce-0.4Zn (wt.%) alloy achieving fracture elongation (FEL) of ∼33.6 %, with a remarkable FEL improvement by 100 % in comparison to Zn-free counterpart. Meanwhile, the tensile yield strength (TYS, 195.5 MPa) is increased by ∼27.5 MPa after trace Zn addition. Although trace Zn addition improves the fraction of GBs with high misorientation, it reconciles crack tolerance with enhanced strength. The introduction of Zn not only promotes pyramidal 〈 c + a 〉 slips and inhibits twinning nucleation, but also enhances the GB cohesion by Zn segregation. Based on in-situ microstructure observation, we found that the enhanced GB cohesion enables the segregation-inspired hierarchical crack buffering, as well as deflecting and branching. Enhanced GBs can also facilitate the continuous emission of 〈 c + a 〉 dislocations in neighboring grains irrespective of the onset of microcracks, forming a plastic zone to retard local strain concentration, thus avoiding microcrack percolation and attaining a crack-mediated elongation reserve of above 15 %. Besides, the higher TYS in the Zn-containing alloy mainly stems from the enhanced solid-solution strengthening of Zn solutes, thus achieving strength and crack tolerance synergy. [Display omitted] [ABSTRACT FROM AUTHOR]

Here, we successfully prepared (Co 1.5 FeNi) 90 Ti 6 Al 4 high entropy alloy by vacuum arc melting technology, then the alloy was subjected at 800 °C to aging heat treatment for different durations. The results show that the alloy has better phase stability, and the alloys heat-treated under different aging times can maintain a single FCC solid solution structure. The structure of the alloy consists of a γ matrix and a γ′ precipitates. The γ′ precipitates of the alloy after 6h aging treatment is irregularly elliptical until the aging time is increased to 12h, and its shape is transformed into a regular cubic shape. If the aging time is further increased, the shape of the γ′ precipitates will no longer change. The transition of γ′ precipitates from elliptic to cubic results in the decrease of lattice misfit, and the coarsing of γ′ precipitates result in the transition of dislocation from cutting through to Orowan bypass mechanism through γ′ precipitates during deformation. The results of friction and wear show that the alloy has excellent tribological properties. The wear mechanism of the alloy is mainly plough wear and peeling wear, in addition, there is oxidation wear, and the degree of peeling wear becomes serious becomes serious as the aging time increases. • γ′ strengthened high entropy alloys. • The wear mechanism of alloys was systematically studied. • Effect of aging time on phase stability of alloy. [ABSTRACT FROM AUTHOR]

• Plasma Oscillatory Pressure Sintering technology was firstly used to prepare Mo-Si-B alloy, which showed better performance. • The alloy with 9 Hz oscillatory frequency had 97.78% relative density and 11.43 MPa √ m fracture toughness, and its microstructure was refined. • Oscillatory sintering had obvious effect on the closure of micro pores, which was worthy of further research and development of porosity-free structure of Mo-Si-B alloy. [Display omitted] Molybdenum silicon boron alloy is regarded as a new generation of ultra-high temperature alloys and is expected to replace the existing nickel-based alloys. However, the molybdenum silicon boron alloys prepared by powder metallurgy exhibited low density and had many pore defects, which were left hanging in the air. Here, a novel oscillatory sintering method is used to replace the traditional atmospheric sintering. It is found that the addition of the oscillatory frequency improved the density and mechanical properties of the alloy, and made the crystal grains refined to a large extent. It did have certain reference value for the preparation and development of molybdenum silicon boron alloy. [ABSTRACT FROM AUTHOR]

The composition and morphology of the Fe-bearing phase play a significant role in the mechanical properties of aluminum (Al) alloy sheets. In this work, we have studied the formation of Fe-bearing phases in an Al-0.53Mg-0.69Si-0.14Fe (wt%) alloy under the twin-roll casting (TRC) and the direct chill casting (DC) processes, respectively. We found that the π-AlFeMgSi phase was formed in the as-cast TRC sample, while the β-AlFeSi phase was formed in the as-cast DC sample. The differences in the formation of Fe-bearing phases are attributed to the promotion of the peritectic reaction to form the π-AlFeMgSi phase via the TRC process. Furthermore, after homogenization treatment at 550 °C and 2 h, the π-AlFeMgSi phase in the as-cast TRC sample completely decomposed into the fine β-AlFeSi phase, while it was insufficient to dissolve the β-AlFeSi phase in the as-cast DC sample. This is owing to the lower dissolution temperature of the π-AlFeMgSi phase compared to the β-AlFeSi phase. The decomposition of the π-AlFeMgSi phase expands the solid solubility and promotes the aging precipitation, resulting in higher yield strength of the TRC sample than that of the DC sample during the peak-aging treatment. Our work provides new insight into the development of high-performance AA6xxx series alloys based on the TRC process. ● The π-AlFeMgSi phase was found in the as-cast twin-roll casting (TRC) sample. ● The homogenization treatment of 550 °C -2 h can make the π-AlFeMgSi phase dissolved. ● The mechanism of TRC phase formation was revealed. ● Microstructure and tensile properties of TRC AA6005 aluminum sheet were studied. [ABSTRACT FROM AUTHOR]

Abstract: A facile growth procedure of low-pressure chemical vapor deposition has been developed to synthesize single crystal TiO2 nanorods on Ni-coated Ti substrate. The results indicate that the as-prepared nanorods are high purity single crystal with a [110] preferential orientation. Using directly the nanorods as emitters, their field emission (FE) properties have been investigated. The turn-on field of the nanorods decreases from 3.96V/μm to 2.98, and 2.16V/μm as the growth temperature increases from 700°C to 750, and 800°C, respectively. In addition, the nanorods show good FE stability during 480min. Such behavior is mainly related to the morphology of nanorods, which depends on the growth temperature. Also, the growth mechanisms of the nanorods are analyzed in detail based on the experimental results. [Copyright &y& Elsevier]

Abstract: Natural zeolite supported Cr-doped TiO2 photocatalysts were synthesized for the sake of improving the recovery and photocatalytic efficiency of TiO2. The materials were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface areas, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflection spectroscopy (UV–vis DRS) and photoluminescence (PL). The photocatalytic activity was evaluated by the degradation of methyl orange in aqueous solution. The results show that the Cr concentration and the calcination temperature play important role on the microstructure and photocatalytic activity of the samples. The 10mol% Cr-doped TiO2/zeolite calcined at 400°C exhibits higher photocatalytic activity than that of the other samples. [Copyright &y& Elsevier]

Abstract: In this study, the FeS/ferroalloy composite coating with the upper FeS coating and the lower ferroalloy welding coating was prepared on the 1045 steel by a compound technology—metal-arc inert-gas (MIG) welding and low temperature ion sulfurizing. The surface morphologies, phase structure and mechanical properties of the FeS/ferroalloy composite coating have been characterized by surface analysis methods such as scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and nano-indentation tester. The SEM images showed that the surface of the FeS/ferroalloy composite coating was homogeneous and smooth, and the thickness of the FeS layer obtained from ion sulfurizing was about 3μm. The EDS analysis results proved that the light gray belt zone in the cross-section morphology was the FeS layer. The XRD patterns implied the FeS/ferroalloy composite coating was composed of FeS, α-Fe and Fe–C solid solution. The coated disc slided against an AISI 52100 ball under dry friction condition. The results showed that the FeS/ferroalloy composite coating exhibited low friction coefficient and high wear-resistance. [Copyright &y& Elsevier]

Abstract: Natural zeolite supported Fe3+-TiO2 photocatalysts were synthesized for the sake of improving the recovery and photocatalytic efficiency of TiO2. The as-prepared materials were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflection spectroscopy (UV–vis DRS), scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). Methyl orange was used to estimate the photocatalytic activity of the samples. The results showed that zeolite inhibited the growth of TiO2 crystallite sizes. The Fe3+ concentration played an important role on the microstructure and photocatalytic activity of the samples. The iron ions could diffuse into TiO2 lattice to the form Fe–O–Ti bond and gave TiO2 the capacity to absorb light at lower energy levels. The photocatalytic activity of the samples could be enhanced as appropriate dosages of Fe3+ were doped. [Copyright &y& Elsevier]

Abstract: The effects of primary quinoline insoluble (PQI) on the formation process of mesocarbon microbeads (MCMBs) have been investigated through comparison of microstructural characteristics of PQI and MCMBs, which were comprehensively identified by Fourier transform infrared, solid-state 13C nuclear magnetic resonance and X-ray diffraction. The results showed that PQI had similar polyaromatic structure to MCMBs in terms of carbon aromaticity, which indicated that PQI could overcome the high energy barrier of a new mesophase formation and decrease the activation energy of MCMBs formation. Thus, it was concluded that PQI could act as the nuclei for mesophase growth. The nucleation of PQI was further justified by the of-course growth of the secondary MCMBs. [ABSTRACT FROM AUTHOR]

Abstract: Activated phenol resin-based carbon spheres (APCS) electrodes with high double layer capacitance and good rate capability were prepared from phenol resin-based spheres (PS) at different carbonization temperatures prior to KOH activation. The carbonization temperature has a marked effect on both the pore structure and the electrochemical performances of the APCS in 6M KOH electrolyte. APCS carbonized at 600°C results in higher specific surface area and larger pore size, and hence higher capacitance and better rate capability. The specific capacitance of the APCS in 6M KOH aqueous solution can be as high as 282Fg−1. It remains 252Fg−1 as the current density increases to 1000mAg−1. [Copyright &y& Elsevier]

Abstract: Potato starch-based activated carbon spheres (PACS) were prepared from potato starch by stabilization, carbonization followed by activation with KOH. The obtained PACS are hollow and retain the original morphology of potato starch with decrease in size, as shown by scanning electron microscopy. Modification of textural properties of the PACS was achieved by varying the carbonization temperature and the ratio of KOH/PCS. The results of N2 adsorption isotherms indicate that the samples prepared are mainly microporous. The electrochemical behaviors of the hollow PACS were studied by galvanostatic charge–discharge, cyclic voltammetry, and impedance spectroscopy. The results indicate that high specific capacitance of 335F/g is obtained at current density 50mA/g for PACS with specific surface area 2342m2/g. Only a slight decrease in capacitance, to 314F/g, was observed when the current density increases to 1000mA/g, indicating a stable electrochemical property. [Copyright &y& Elsevier]

Abstract: The 3Cr13 coating was prepared on the surface of 1045 steel by high velocity arc spraying method, and then treated by low temperature ion sulfuration to obtain the solid lubrication composite 3Cr13/FeS layer. SEM was used to observe the surface, cross-section and worn scar morphologies. XRD was utilized to analyze the phase structure. X-ray stress determinator was utilized to measure its residual stress. The nano-hardness and elastic modulus of composite 3Cr13/FeS layer were surveyed by the nano-indentation tester. The tribological properties were investigated on a ball-on-disk wear tester under dry and oil lubrication conditions. The results showed that the friction coefficient and wear scar depth of the composite 3Cr13/FeS layer were always lower than those of FeS film and 1045 steel under dry and oil lubrication conditions. Therefore the composite 3Cr13/FeS layer had excellent Friction-reduction and anti-wear properties. [Copyright &y& Elsevier]

The mechanical properties of Al-Cu-Li alloys after different pretreatments were investigated through tensile testing at 25 and −196 °C, and the corresponding microstructure characteristics were obtained through optical metallography, scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy. An increasing mechanism of both strength and ductility at cryogenic temperatures was revealed. The results show that the hot deformation pretreatment before homogenization promoted the precipitation of Al3Zr particles, improved particle distribution, and inhibited local precipitation-free zones (PFZ). Both hot deformation pretreatment before homogenization and cryogenic temperature were able to improve strength and ductility. The former improved strength by promoting the precipitation of Al3Zr particles while enhancing the strengthening effect of the second-phase particles and reducing the thickness of the coarse-grained layer. Meanwhile, the increase in ductility is attributable to the decrease in thickness of the coarse-grained layer, which reduced the deformation incompatibility between the coarse and fine grains and increased the strain-hardening index. The latter improved the strength by suppressing dynamic recovery during the deformation process, increasing the dislocation density, and enhancing the work hardening effect. Additionally, the increase in ductility is attributable to the suppression of planar slip and strengthening of grain boundaries, which promoted the deformation in grain interiors and made the deformation more uniform. [ABSTRACT FROM AUTHOR]

Abstract  The Cysteamine/DNA/SWNTs-film-modified Au electrode was successfully prepared, and its electrochemical behavior is investigated by cyclic voltammetry (CV). The modified electrode exhibited a pair of stable and well-defined redox peaks, with the formal potentials (E 0′ at about −0.032 V (vs. SCE) in 0.1 M pH 7.0 phosphate buffer solution (PBS). The dependence of E 0′ on solution pH indicated that the direct electron transfer reaction of the Cysteamine/DNA/SWNTs film is the same electron transfer coupled with the proton participating in the reaction process. Taxol is an anticancer drug; it interacts with microtubule proteins in a manner that catalyzes the formation of microtubules from tubulin and stabilizes the resulting structures. Using the Cysteamine/DNA/SWNTs-film-modified Au electrode, we study the interaction between DNA and Taxol studied. A UV-Vis experiment is performed to confirm this interaction. [ABSTRACT FROM AUTHOR]

Abstract: Ultrathin sections prepared from both transverse and longitudinal PAN precursor fibers were examined by high-resolution transmission electron microscopy. Ordered and amorphous phases coexist in these sections, providing verification for the two-phase structure of PAN fibers, however, onion-like spheres and crystallites predominate in the transverse sections, and highly oriented structures are dominant in the longitudinal sections. The formation of the onion-like spheres can be ascribed to intramolecular and intermolecular dipolar nitrile group interactions. The larger area of oriented structures in the longitudinal sections is due to the coalescence of several ribbons with the approximative orientations. Some defects, such as pores and voids, have also been observed. These examinations provide not only some direct structural evidence but also some information for optimizing spinning technology and for deliberately controlling the microstructures to obtain PAN precursor fibers applicable to fabricating high strength carbon fibers. [Copyright &y& Elsevier]

Abstract: In the present experiments, mesocarbon microbeads (MCMBs) were prepared from a coal tar pitch with or without micro-Al2O3 powder under 410 °C for 7 h to study the influence of alumina on the MCMBs. OM, SEM, XRD and EDS were used to analyze the as-received MCMBs, among which SEM was used firstly to observe the microtextures of MCMBs systemically. The results show that the irregular alumina particles, which have been enwrapped in the MCMBs, impede the growth of the mesophase spheres and consequently decrease the yield of them. The textural layers of the formed MCMBs were disturbed by the aluminum oxide particles. Although the alumina in the spheres could escape and seems to maintain the sphericity of MCMBs during the graphitization, the bad influence would remain. In addition, ash analysis of MCMBs was carried out, which further confirmed the existence of alumina particles in the as-received spheres and the absence of them in the graphitized spheres. In conclusion, alumina in raw pitches is disadvantageous for the growth and the final structure of MCMBs and should be removed in advance if high yield and regular structure are expected. [Copyright &y& Elsevier]

• The eutectic Mg 2 Si in Al-11Mg 2 Si alloy was modified to spherical particles with 0.2 wt% Ca-Sb addition. • Adding 1.0 wt% Ca-Sb resulted in a microstructure transition from hypoeutectic to hypereutectic characteristics in Al-11Mg 2 Si alloy. • The 0.2 wt% Ca-Sb modified alloy exhibits an improvement in elongation to failure and ultimate tensile strength. • The modification mechanisms and the reasons for the enhanced mechanical properties were discussed in detail. The combined addition of 0.2 wt% Ca-Sb in Al-11Mg 2 Si alloy led to significant refinement of the eutectic Mg 2 Si from a coarse, needle-like morphology to spherical particles. Specifically, a further increase of Ca-Sb addition to 1.0 wt% resulted in the microstructure transition from hypoeutectic to hypereutectic characteristics. The refinement of eutectic Mg 2 Si could be attributed to the selective adsorption of Ca and Sb atoms on Mg 2 Si surfaces, which inhibited the growth of the eutectic phase in the preferential growth direction. Importantly, Ca and Sb elements were involved in the formation of heterogeneous nuclei for primary Mg 2 Si when Ca-Sb content increased to 1.0 wt%, which introduced the transition of composition from hypoeutectic to hypereutectic structures. Comparing to the unmodified alloy, the Al-11Mg 2 Si alloy modified with 0.2 wt% Ca-Sb exhibited significantly enhanced elongation to failure of ~7.9% (from ~1.3% of the unmodified alloy) and ultimate tensile strength of ~222 MPa (from ~180 MPa of unmodified alloy). The spheroidization of eutectic Mg 2 Si after complex modification is believed to be the underlying reason for the greatly enhanced tensile properties. [ABSTRACT FROM AUTHOR]

The effects of Zn and Mg content in thin-walled square extrusions of Al-Zn-Mg alloys on its crashworthiness were investigated, and the correlation between the crushing properties, mechanical properties, and microstructures of the profiles were investigated. The results showed that the strength and the compression properties were gradually increased with a decrease in the Zn/Mg ratios (from 12.48 to 4.57). When the Zn/Mg ratio is lower (less than 6.29), an increase in the Mg content simultaneously improves the alloy strength and the compression properties. An increase in Zn content (from 5.07 to 6.77) can improve the strength of the alloy however, it does not affect the compression properties. However, the higher Zn contents (6.77%) would lead to cracking in advance during the compressing, which reduces the compression energy absorption capacities of the product. Therefore, in order to obtain higher strength and excellent compression properties, the Zn/Mg ratio should be reduced. For the upper limit, the Zn content should not be too high (less than 6.77), as this may lead to early cracking and failure. For the lower limit, the Mg content should be higher (more than 0.91) to make sure that the alloy has excellent compression properties and higher strength. [ABSTRACT FROM AUTHOR]

CoCrFeMnNi high entropy alloy films (HEAFs) manifest excellent properties as the potential structural materials in the microelectro-mechanical systems (MEMS). In this work, we systematically investigated the growth, microstructure and mechanical properties of CoCrFeMnNi HEAFs with thicknesses varying from 300 to 1400 nm. The film growth study revealed that ~300 nm of the amorphous layer, ~250 nm of the crystalline layer, and the preferred orientation layer grew sequentially during the deposition process. Results from nanoindentation with dynamic mechanical analyses showed that the mechanical properties of CoCrFeMnNi HEAFs depended on the film thickness. Both the hardness and Young's modulus decreased first and then increased with the increasing film thickness. The mechanical properties were related to the microstructures of the three layers. The nonuniform structure of the 750 nm-thick film could lead to the low and uneven mechanical properties. However, the abundant nanotwins in the 1400 nm-thick film resulted in the strengthening effect. Our findings not only provide insight into understanding the thickness-dependence of the mechanical properties of CoCrFeMnNi HEAFs, but also offer clues for the MEMS to design high performance HEAFs at small-scales. • We deposited high entropy alloy films with different thicknesses and structures. • Amorphous, crystalline and preferred orientation layers grew sequentially in films. • Used dynamic mechanical analyses to probe thickness-dependent mechanical properties. • We correlated mechanical properties with structures of the three layers in the film. • Nanotwins and small grain sizes in films contributed to the strengthening effect. [ABSTRACT FROM AUTHOR]

Effects of Sb modification on the eutectic microstructure and tensile properties of hypoeutectic Al–11Mg 2 Si alloy were systematically investigated in this work. Eutectic Mg 2 Si phase in hypoeutectic Al–11Mg 2 Si alloy was successfully refined from the long rod-like structure into fine spherical morphology when introducing 0.2 wt% Sb, whereas 1.0 wt% Sb reversely led to the formation of coarse eutectic Mg 2 Si phase. Specifically, the elongation to failure in the 0.2 wt% Sb modified alloy was significantly improved to 9.7% as compared to the unmodified counterpart (1.5%), and the ultimate tensile strength increased from 183 MPa to 208 MPa. This result can be attributed to the spheroidization of eutectic Mg 2 Si phase with Sb modification, which greatly relieved the stress concentration and restrained the crack source from initiating and propagating. The achieved results could shed new light on a more efficient and economical way to obtain high-performance hypoeutectic Al–Mg 2 Si alloys. [ABSTRACT FROM AUTHOR]

In the present work, CoCrFeMnNiV x (x = 0, 0.07, 0.3, 0.7, 1.1) high entropy alloy films were fabricated by magnetron co-sputtering. For low contents of V, typical face-centered cubic (fcc) peaks were identified in X-ray diffraction patterns. With the increasing V content, the diffraction peaks became broadened and the formation of an amorphous phase was promoted. TEM observations showed abundant nanotwins in the films with low V contents and the transition from fcc to the amorphous structure with the increasing V content. Mechanical properties of the films were studied using nanoindentation and micro-pillar compression tests. The films exhibited a high hardness ranging from 6.8 to 8.7 GPa. The serrated flow associated with shear banding showed in the stress-strain curves for films with x ≥ 0.3. When x = 0.07, the excellent yield strength of 3.79 GPa and ultimate compressive strength of 4.93 GPa were achieved with little sacrifice in ductility. The presence of nanotwins contributed to the strain hardening effect. Image 1 • We fabricated CoCrFeMnNiV x high entropy alloy films by co-sputtering. • Columnar nanograins and high density nanotwins were observed in films. • Nanograins and nanotwins contributed to strengthening with good ductility. • Detwinning behavior in films was observed during micro-pillar compression test. • The formation of an amorphous phase was promoted with the increasing V content. [ABSTRACT FROM AUTHOR]

Designing an alloy with both high strength and high ductility is a daunting challenge for structural materials. CoCrFeMnNi high-entropy alloy with FCC structure has been proven to be an ultra-ductile but low-strength alloy. Precipitation hardening is an effective way to solve this problem. However, the precipitation mechanisms are generally complex during the solidification process because of the composition with five or more elements in high-entropy alloys. We reported a designing concept that the liquid phase separation was used to simplify the mechanism of precipitates formation. The doped Nd separated from the matrix and precipitated with Ni and Mn because of the negative mixing enthalpy. Precipitation occurred randomly at grain boundaries and in the interior of grains. Compared to the single-phase FCC matrix, the hardness of HCP precipitates was three times of the matrix. The alloys were strengthened with good ductility and it was demonstrated by uniaxial tension tests. [ABSTRACT FROM AUTHOR]

Highlights • The development of a second-order scheme that describes the annealing of Metal-Intermetallic Laminate composites. • Numerical analysis on the convergence order is rigorously established, confirming expected discretization accuracy. • The formation of Al-rich and Ni-rich layers and diffusion paths in a ternary phase diagram show nice agreements with experimental data. • The numerical simulation results show nice agreements with experimental data. Abstract Metal–Intermetallic Laminate (MIL) composites are laminate structures that are fabricated by optimizing unique benefits of constituent components to have attractive physical and mechanical features, such as high strength, stiffness, and toughness. The synthesis of MIL composites involves annealing reaction of multiple metallic elements at high temperatures. In this work, we propose, analyze, and implement a second-order semi-implicit scheme for the annealing of a ternary metallic reaction system. The robustness of such a numerical scheme is demonstrated by various numerical experiments, as well as the expected accuracy tests. At the theoretical level, we provide a detailed convergence analysis, which confirms the second-order accuracy in both the temporal and spatial discretization. Moreover, this numerical scheme is used to study the annealing process of the Al–Fe–Ni ternary system. The computation reproduces the formation of the Al-rich and Ni-rich layers in the annealing process. We present the computational results as diffusion paths in a ternary phase diagram, with a nice agreement with that of experimental data. We also study the growth kinetics of the two layers by calculating the rate constant and kinetic exponent of the reaction. The morphology of interfaces between different layers is thoroughly investigated as well. The computational results indicate that the numerical scheme is an effective, useful tool for predicting the microstructure evolution in the annealing process of a ternary reaction system. [ABSTRACT FROM AUTHOR]

Modulating the charge‐transfer pathway is of great significance for boosting the photocatalytic efficiency of the catalysts. Herein, well‐ordered Al doping SrTiO3/TiO2 heterojunction nanorod arrays (Al‐STO/TiO2 HNRAs) via a two‐step hydrothermal protocol for efficient piezo‐photocatalysis are reported. The piezoelectric field generated by the internal polarization of Al‐STO/TiO2 HNRAs can be tailored by Al doping content, which could help to modulate the migration and separation of charge carriers. The doping of Al also makes the charge lifetime from 1.14 ns increased to 1.76 ns. Under the co‐excitation of ultrasonic and ultraviolet irradiation, the oxidation rate constant of Al‐STO/TiO2 HNRAs can reach 0.037 min−1 for the degradation of Rhodamine B molecules, which was 3.42 times higher than that of the un‐doping sample. The piezo‐potential distribution and charge migration within Al‐STO/TiO2 HNRAs were explored by piezoelectric force microscopy and COMSOL simulation. This work provides a promising solution toward modulating charge carrier migration for boosting photocatalytic activities with the assistance of mechanic vibration. [ABSTRACT FROM AUTHOR]

Fine structured targets are promising in enhancing laser-driven proton acceleration for various applications. Here, we apply 3D-printed microwire-array (MWA) structure to boost the energy conversion efficiency from laser to proton beam. Under irradiation of high contrast femtosecond laser pulse, the MWA target generates over 1.2 × 1012 protons (>1 MeV) with cut-off energies extending to 25 MeV, corresponding to top-end of 8.7% energy conversion efficiency. When comparing to flat foils the efficiency is enhanced by three times, while the cut-off energy is increased by 32%. We find the dependence of proton energy/conversion-efficiency on the spacing of the MWA. The experimental trend is well reproduced by hydrodynamic and Particle-In-Cell simulations, which reveal the modulation of pre-plasma profile induced by laser diffraction within the fine structures. Our work validates the use of 3D-printed micro-structures to produce high efficiency laser-driven particle sources and pointed out the effect in optimizing the experimental conditions. The performance of laser-driven ion accelerators is intimately linked to the structure of the target. Here, laser-proton acceleration from a 3D-printed microwire-array target boosts the conversion efficiency and cut-off energy compared to a flat foil. [ABSTRACT FROM AUTHOR]

Abstract: By simulating the cuticles of some soil animals, a combination of soft part (untreated substrate) and hard part (laser remelting area) structure was designed on metal surface to get an improved performance. Different specimens were prepared which contained units with micro and nano scale grains. The microstructures were observed by environmental field emission scanning electron microscopy. X-ray diffraction was used to identify the phases. The results of these tests indicate that due to the rapid solidification condition in the water, nano scale grains have a high microhardness between 1300 and 1000HV. Retained austenite was found in it. Some of them transform to martensite in block on ring wear test. Specimens with bionic unit have a better wear resistance. Especially, the units with nano grains bring a further enhancement. The alternate soft and hard in macroscopic (substrate and laser remelting area) and microscopic (austenite and martensite) structure played a key role in improving the H13 wear resistance. [Copyright &y& Elsevier]

Abstract: The manufacture of the micro-structure of MEMS (Micro Electro-Mechanical System) becomes more and more important in recent years. Electrochemical micromachining has many advantages over other machining methods. However, a tiny electrode is needed to manufacture the micro-structures. Accordingly, in this study pulsed electrochemical machining is applied to fabricate a cylindrical microelectrode. The influences of working parameters (such as applied voltage, pulsed period, duty factor and temperature) on the fabrication of the microelectrode are discussed. Results also show that cylindrical tungsten microelectrodes with a diameter of 100μm and various lengths can be fabricated by a linear decay of applied voltage or duty factor. [Copyright &y& Elsevier]

Abstract: Stimulated by the cuticles of soil animals, an attempt to improve the wear resistance of compact graphite cast iron (CGI) with biomimetic units on the surface was made by using a biomimetic coupled laser remelting process in air and various thicknesses water film, respectively. The microstructures of biomimetic units were examined by scanning electron microscope and X-ray diffraction was used to describe the microstructure and identify the phases in the melted zone. Microhardness was measured and the wear behaviors of biomimetic specimens as functions of different mediums as well as various water film thicknesses were investigated under dry sliding condition, respectively. The results indicated that the microstructure zones in the biomimetic specimens processed with water film are refined compared with that processed in air and had better wear resistance increased by 60%, the microhardness of biomimetic units has been improved significantly. The application of water film provided finer microstructures and much more regular grain shape in biomimetic units, which played a key role in improving the friction properties and wear resistance of CGI. [Copyright &y& Elsevier]

Abstract: The process of wetting of Al2O3p/6061Al substrate by Zn–Al filler metal in air was investigated. The filler was found to wet the substrate by undermining the oxide layer on the substrate. Dynamic observations of substrate oxide undermining, conducted using conventional illumination and recording, were correlated with post-cooling microscopy and analysis. The undermining mechanisms were discussed and the influences of temperature, surface roughness and gas evolution on the propagation of undermining were examined. The Zn–Al filler droplet exhibited excellent wettability to the Al2O3p/6061Al substrate via undermining and it completely spread on the substrate in the end. Spreading of the filler was found to be rapid before the filler droplet was depleted, wherein the increase of the undermining region radius was a linear function of time. However, after the depletion of filler droplet, the spreading became significantly sluggish and negligible further undermining was observed. The current wetting system was non-reactive and the linear spreading was believed to be associated with the presence of a precursor film showing up ahead of the macroscopically observable spreading front. The undermining velocity at the ‘linear’ spreading stage was independent of the volume of the filler droplet, but increased linearly with temperature. The propagation of undermining was much rapider on the substrate with higher roughness and was encouraged by the escaping of gaseous products from the substrate. [Copyright &y& Elsevier]

Abstract: Tetrahedral amorphous carbon (ta-C) film was deposited on silicon coupons using a Filtered Cathodic Vacuum Arc system with a pre-implantation process, and then was investigated by some systematic analyses. The ta-C film shows a very smooth surface morphology and a dense cross-section texture, along with a gradient interlayer, about 0.5 μm between the substrate and ta-C film, also has a board distribution of asymmetric Raman intensity in the range of 1200–1700 cm−1, centered at 1567 cm−1. Microhardness and elastic modulus of ta-C film are 47.74 GPa and 298.46 GPa, respectively. Ta-C film also possesses a good adhesion, critical load (Lc) of 42 mN. Moreover, the ta-C film owns a low friction coefficient of about 0.15 in a long duration. [Copyright &y& Elsevier]

The microstructure, mechanical properties, and oxidation behavior of Mo–10Si–8B- x TiC (at.%, x = 0,5,10,15) alloys fabricated via oscillatory pressure sintering are studied. The phase constitution of three TiC-added alloys is α-Mo + Mo 3 Si + Mo 5 SiB 2 + Mo 2 C + TiC; in 15TiC alloy α-Mo phase no longer maintains its contiguity as in the other three alloys. With further TiC addition, the microhardness improves by 60–90 % (up to 1500 HV), Young's elastic modulus increases from 328 to 368 GPa, and the fracture toughness decreases from 14.23 to 10.8 MPa m1/2, accounting for the less-ductile phase and newly introduced brittle phases. Thermogravimetric analysis indicates that the addition of TiC reduces the oxidation resistance. For isothermal oxidation at 800, 1000, and 1200 °C, the serious oxidation occurs for all TiC-added alloys except for 15TiC alloy at 1200 °C because the oxidation sequence changes to TiC → Mo 5 SiB 2 → Mo 3 Si → α-Mo. The anomalous phenomenon for 15TiC alloy at 1200 °C could be attributed to the rapid formation and cover of protective SiO 2 –TiO 2 layer on alloy surface after the transient MoO 3 volatilization. • Comprehensively study microstructure and performance of Mo–10Si–8B- x TiC alloys. • Apply oscillatory pressure sintering to fabricate alloys. • Young's elastic modulus and microhardness improves with TiC content, Poisson's ratio and fracture toughness reverse. • Determine phases oxidation sequence as TiC → Mo 5 SiB 2 → Mo 3 Si → α-Mo from a thermodynamic perspective [ABSTRACT FROM AUTHOR]

• A high strength and ductility AZT522 alloy was developed to compete with AZ91 alloy. • The AZT522 alloy had much finer as-cast microstructure than AZ91 alloy. • The AZT522 alloy exhibited superior rolling formability to the AZ91 alloy. • The annealed AZT522 alloy showed higher strength and ductility than AZ91 alloy. A novel Mg-5.34Al-2.23Zn-1.73Sn (wt%, AZT522 for short) alloy with high strength-ductility synergy was designed and fabricated via simple hot rolling and annealing treatment to compete with the commonly used Mg-9Al-1Zn-0.2Mn (wt%, AZ91) alloy. Different from the coarse microstructure of the as-cast AZ91 alloy, the as-cast AZT522 alloy has much finer microstructure, which consists of finer dendrites and smaller second phase particles. Hot rolling was carried out on the solution-treated alloys to effectively refine the microstructure and improve the mechanical properties. The results suggest that the AZT522 alloy shows better rolling formability. Then, the hot-rolled AZT522 alloy was annealed at the optimized parameter, i.e., 225 °C/1.5 h, leading to uniform fine grains with an average size of ~2.3 µm and numerous near-spherical precipitates (Mg 17 Al 12 and Mg 2 Sn) with a mean diameter of ~90 nm. Benefiting from the fine annealing microstructure, the novel AZT522 alloy finally exhibited high tensile properties at room temperature, i.e., ultimate tensile strength (UTS) of ~343 MPa, yield strength (YS) ~271 MPa, and elongation to failure (δ f) ~16%, which is a much better combination of strength and ductility than the annealed AZ91 alloy. This novel AZT522 alloy may provide a new insight to develop commercial high strength and ductility Mg alloys. [ABSTRACT FROM AUTHOR]

Diffusion bonding is an effective method for joining dissimilar materials. In this study, dissimilar metals of MA956 steel and tungsten (W) were diffusion bonded with Ni/Nb composite interlayer. The experiments were carried out at 1 0 5 0 ∘ C , 20 MPa for 20 min in vacuum by spark plasma sintering (SPS) technique. The microstructure and mechanical properties of the bonded joints were evaluated. SEM images and the results of elementary composition indicate that no intermetallics formed at Ni/MA956 steel and Nb/W interfaces, but Ni 6 Nb 7 and Ni 3 Nb formed at the Nb/Ni interface. Compared with the directly bonded joint between W and MA956 steel, the average shear strength of the joint with Nb/Ni composite interlayer significantly increased to 270 MPa. Although the result of joint residual stresses simulation shows that the maximum residual stress was near the W substrate, the joints with composite interlayer in shear experiments fractured at Nb/Ni interface. The hardness changes along joint interfaces indicate the formation of intermetallic compounds and solid solution phases in the diffusion layers. [ABSTRACT FROM AUTHOR]

Ultrafine HfB2 powders were synthesized by the combination of borothermal reduction of HfO2 and solid solution of 5 mol% TiB2 or 5 mol% TaB2, prototypically, (Hf0.95Ti0.05)B2 and (Hf0.95Ta0.05)B2. The influence of substitution on the particle growth, high‐temperature stability, densification, microstructure, and mechanical properties of HfB2 was investigated. Results showed that the particle sizes of HfB2, (Hf0.95Ti0.05)B2 and (Hf0.95Ta0.05)B2 powders prepared by borothermal reduction at 1500°C were 1.73, 0.87, and 0.21 µm, respectively. The substitution of TaB2 led to a greater decrease in particles size than TiB2. After heat treatment at 1800°C, the particle sizes of HfB2, (Hf0.95Ti0.05)B2 and (Hf0.95Ta0.05)B2 powders increased to 2.60, 1.59, and 0.32 µm, respectively, indicative of the good high‐temperature stability of TaB2‐substituted HfB2. The relative densities of HfB2, (Hf0.95Ti0.05)B2 and (Hf0.95Ta0.05)B2 ceramics after spark plasma sintering at 2000°C were 76.1%, 85.2% and 99.8%, respectively. The fully dense (Hf0.95Ta0.05)B2 ceramics with fine microstructure showed comparably high Vickers hardness of 21.1 GPa combined with flexural strength of 521.2 MPa. It was proved that the solid solution of TaB2 could effectively inhibit the grain growth of HfB2 powders, and improve the densification, microstructure, and mechanical properties of HfB2 ceramics. [ABSTRACT FROM AUTHOR]