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Abstract: Y(NO3)3·6H2O-doped ZnO–Bi2O3-based varistor ceramics were prepared using a solid reaction route. The microstructure, electrical properties, degradation coefficient (D V), and dielectric characteristics of varistor ceramics were studied in this paper. With increasing amounts of Y(NO3)3·6H2O in the starting composition, Y-containing Bi-rich, Y2O3, and Sb2O4 phases were formed, and the average grain size decreased. Results also showed that with the addition of 0.16mol% Y(NO3)3·6H2O, Y(NO3)3·6H2O -doped ZnO-based varistor ceramics exhibit comparatively better comprehensive electrical properties, such as a threshold voltage of 425V/mm, a nonlinear coefficient of 73.9, a leakage current of 1.78μA, and a degradation coefficient of 1.7. The dielectric characteristics and lightning surge test also received the same additional content of Y(NO3)3·6H2O. The results confirmed that doping with rare earth nitrates instead of rare earth oxides is very promising route in preparing high-performance ZnO–Bi2O3-based varistor ceramics. [Copyright &y& Elsevier]

Strain-induced precipitation was systematically investigated in austenitic Inconel 617B superalloy (IN617B) after deformation of 0.2 true strain in its service temperature range (700–850 °C). The precipitation-time-temperature (PTT) curves obtained by stress relaxation experiments showed a classic C-shape with the nose temperature of 800 °C, and a minimum incubation period of 30 s, and the main strain-induced precipitate was M 23 C 6 carbide. After specimens deformed at 800 °C to a strain of 0.2 were held between 10 and 1000 s, they underwent a second-pass strain test, during which the M 23 C 6 precipitates evolved and influenced the flow stress; this behavior was investigated. During the nucleation, growth, and coarsening of the strain-induced precipitates, the morphology of the M 23 C 6 particles gradually changed from spherical to polygonal with increasing size, but the precipitates always maintained their cube-on-cube orientational relationship with the austenitic matrix. During the nucleation stage before 30 s, many pre-precipitation clusters and weak static recovery softening led to low second-deformation flow stress, which persisted at approximately 630 MPa. In the precipitation growth phase before 360 s, recovery softening balanced precipitation hardening. The strain-induced precipitates grew larger, and they were able to pin dislocations. In addition, some complex microstructures resulting from particle collisions were observed. This resulted in the maximum rate of increase of the second deformation flow stress, which quickly reached almost 700 MPa. When the holding time was extended to 1000 s, the recovery softening effect further increased, while the M 23 C 6 particles gradually coarsened; this weakened the increasing trend of the second deformation flow stress, which increased to only 715 MPa at 1000 s • The strain-induced precipitate in IN617B alloy is dominated by M 23 C 6 carbide in the temperature range of 700–850 °C. • Morphological evolution mechanism of the strain-induced precipitates M23C6 in IN617B alloy. • M 23 C 6 has different degrees of hardening effect on the matrix during nucleation, growth, and coarsening processes. [ABSTRACT FROM AUTHOR]

A new type of Ti-18.4 Nb-1.4Zr-0.3Ta-4.3 O exhibiting near-linear deformation behavior was created to elucidate the core principles behind its near-linear deformation behavior in quasi-Gum Metals. The in situ simultaneous X-ray diffraction study shows that a β→α″ stress-induced martensitic transformation (SIMT) persists and covers a large stress range under the near-linear deformation of Ti-18.4 Nb-1.4Zr-0.3Ta-4.3 O. Within the SIMT process, the variant 5 of α″ martensite usually forms more readily as it can output the maximum phase transformation strains compared to the other equivalent variants. The experimental results indicate that near-linear deformability of quasi-Gum Metal is due to the combined influence of its inherent deformation (including elastic and trace plastic) together with a SIMT that operates over a large strain range. These findings have helped to develop a more comprehensive view of the principle behind the near-linear deformation in quasi-Gum Metals and Gum Metal. • A quasi-Gum Metal with near-linear deformation behavior consisting of Ti-18.4 Nb-1.4Zr-0.3Ta-4.3 O was designed. • The near-linear deformation mechanism of this alloy was studied. • The combined effect of inherent deformation together with the SIMT contributes to the near-linear deformability. [ABSTRACT FROM AUTHOR]

With the assistance of thermo-mechanical treatment, an attempt was made to fabricate a simple binary Ti–38Nb (wt.%) alloy with low modulus and high strength. The martensitic transformation from β to α″ occurred in the solution-treated Ti–38Nb alloy, resulting in low yield strength. Upon a cold rolling plus annealing at 673 K for 40 min, a lot of dislocations and grain boundaries were introduced in the Ti–38Nb alloy, which played key roles in inhibiting the martensitic transformation and retarding the precipitation of ω. Therefore, overwhelming β phase with low content of β-stabilizers can survive at room temperature, giving rise to a low modulus of 56 GPa. Meanwhile, the Ti–38Nb alloy was remarkably reinforced, with a yield strength of 850 MPa and a ultimate tensile strength of 1020 MPa, because of the inhibition of α″ martensitic transformation. As a result, the cold rolled plus annealed Ti–38Nb alloy can exhibit higher strength-to-modulus ratio than those of the current implant materials and thereby has high potential applications in hard tissue replacements. [ABSTRACT FROM AUTHOR]

Abstract: The effects of high-energy ultrasonic field on the microstructure and mechanical properties of A356 alloy are investigated. The results indicate that the long dendritic silicon phases are broken into pieces and the considerable improvement of mechanical properties can be achieved due to the ultrasonic treating. Especially, when the value of the ultrasonic power is 1.2kW, the distribution of the silicon phase is approximately uniform and the morphology of α-Al phase presents approximate ball-shape. The tensile strength σ b, yield stress σ s and elongation δ are 293.85MPa, 207.34MPa and 6.98%, which are 1.55, 1.93 and 1.10 times to that of without high-energy ultrasonic treating, respectively. These are due to the mechanical effects, cavitation effects and acoustic streaming effects induced by the high-power ultrasonic field. The influence mechanisms of high-energy ultrasonic treatment are discussed in detail. [Copyright &y& Elsevier]

In this study, a (β+α") dual-phase Ti-33Nb-4Sn alloy was successfully fabricated by a designated severe cold rolling plus pre-deformation (CRP) treatment to display a linear deformation behavior. Upon CRP treatment, a high density of dislocation tangles and grain refinement were induced into the Ti-33Nb-4Sn alloy consisting mainly of α" martensite as well as some retained β parent phase. Due to the retardation effect of dislocations and grain boundaries on martensitic transformation, the slight stress induced martensitic (SIM) transformation from β to α" in CRP Ti-33Nb-4Sn alloy covered a wide stress range during loading, together with the linear elastic deformation behavior of β and α" phases. In such a case, the (β+α") dual-phase Ti-33Nb-4Sn alloy exhibited macroscopically linear deformation behavior before yielding. Our results might shed light on design and development of novel (β+α") dual-phase Ti-based alloy with linear deformation behavior for biomedical applications. • A novel (β+α") dual-phase Ti-Nb-Sn alloy was fabricated. • This alloy exhibits linear deformation, instead of stress-plateau, before slip. • The relationship between SIM and deformation behavior was discussed. [ABSTRACT FROM AUTHOR]

In this study, the effects of co-alloying Ti and V on cemented carbide alloys were investigated. Theoretically, the effects of co-alloying Ti and V on structural stability were studied from the perspective of energy stability criteria and elastic stability criteria. The results show that the face-centered-cubic (FCC) structure (W x ,Ti y ,V 1-x-y)C carbides are stable in two domains, one is the WC-poor domain (the concentration of WC is less than 25 at.%), and the other is WC-rich domain (the concentration of WC ranges from 61.5 at.% to 75 at.%). The calculated hardness of FCC structure (W x ,Ti y ,V 1-x-y)C carbide has a maximum of about 27 GPa. As for the hexagonal-close-packed (HCP) structure (W x ,Ti y, V 1-x-y)C carbides, they are stable in WC-rich domain (the concentration of WC is greater than 75 at.%). The calculated hardness of HCP structure (W x ,Ti y ,V 1-x-y)C carbide has a maximum of about 37.2 GPa. Experimentally, the HCP structure (W x ,Ti y ,V 1-x-y)C-8wt.%Co alloy was prepared by mechanical alloying and hot pressing sintering as the HCP structure (W x ,Ti y ,V 1-x-y) C carbide has higher hardness. The results show that, as the concentration of co-alloying Ti and V increases, the hardness of the (W x ,Ti y ,V 1-x-y)C-8 wt.%Co alloy increases, but the fracture toughness of the (W x ,Ti y ,V 1-x-y)C-8 wt.% Co alloy decreases. The effect of co-alloying Ti and V on the hardness can be attributed to the solid solution strengthening and grain refinement strengthening. The achieved hardness of the (W x ,Ti y ,V 1-x-y)C-8 wt.% Co alloy is higher than that of the conventional binary cemented carbide alloys. The tribological properties studies show that co-alloying Ti and V can effectively improve the wear resistance of (W x ,Ti y ,V 1-x-y)C-8 wt.% Co alloys. The main wear mechanism can be attributed to the adhesive wear. • understanding of multialloying effects based on virtual crystal approximation (VCA). • developing the phase diagram for multicomponent hard materials. • guiding optimization on hard materials with enhanced mechanical properties. • guiding optimization on hard materials with enhanced wear resistance. [ABSTRACT FROM AUTHOR]

Abstract Owing to that, efficient cooling the chip demands a heat sink material possess high thermal conductivity and low CTE equivalent to the gallium arsenide (GaAs) or silicon (Si). Addressing this target, we have synthesized Sc 2 W 3 O 12 /Cu composites by hot-pressing sintering at 700 °C, which was based on the uniform submicron Sc 2 W 3 O 12 powder prepared for the first time. The resulting product not only possessed a low CTE (8.31 ppm/K, which was identical to GaAs of 6.2 ppm/K) and high thermal conductivity (243.99 W/m K), but also exhibited extremely stable CTE within a temperature range of 25 °C–300 °C and high Vickers hardness (234.32 HV) due to its uniform and nearly full dense microstructure. A 'thermoelastic-micro-mechanics'model was used to predict the CTE quantitatively and the estimated values were in good agreement with the experimental CTE values. Moreover, the excellent compatibility of thermal properties between Sc 2 W 3 O 12 and Cu possesses an isolated spot in Ashby map based on CTE and thermal conductivity, and the as-synthesized composite exhibits nearly greatest thermal stability indicated via its low thermal distortion parameter (TDP). Highlights • The uniform submicron Sc 2 W 3 O 12 particles were prepared by via high energy ball mill for the first time. • The Sc 2 W 3 O 12 /Cu composites with homogeneous microstructure were synthesized via hot-pressing method. • The Sc 2 W 3 O 12 /Cu composites exhibited extremely stable CTE within a temperature range of 25 °C–300 °C. • The Sc 2 W 3 O 12 /Cu composite obtained at 700 °C possesses high Vickers hardness of 234.32 HV. • The Sc 2 W 3 O 12 /Cu composite realize a good compatibility between high thermal conductivity of Cu and stable NTE property. [ABSTRACT FROM AUTHOR]

By alloying and thermo-mechanical treatment, a novel low-cost metastable β-type Zr-4Mo-4Sn alloy was designed and fabricated for biomedical applications. Upon solution treatment plus quenching, the β-type Zr-4Mo-4Sn alloy exhibits a combination of low Young's modulus (48 GPa) and low magnetic susceptibility (1.22 × 10 −6  cm 3  g −1 ). This low magnetic susceptibility (χ) is reasonably attributed to the choice of alloying components with low χ, i.e., Zr (χ Zr  = 1.32 × 10 −6  cm 3  g −1 ), Mo (χ Mo  = 0.75 × 10 −6  cm 3  g −1 ) and Sn (χ Sn  = 0.03 × 10 −6  cm 3  g −1 ). An analysis of single-crystal elastic constants and Hill approximation indicated that in comparison to binary β-type Ti-based alloys, the present β-type Zr-4Mo-4Sn alloy possesses lower bcc-structural (β-phase) stability represented by its lower C′ and much lower C 44 , resulting in the ultralow Young's modulus of Zr-4Mo-4Sn alloy. [ABSTRACT FROM AUTHOR]

In this study, a novel metastable β-type Zr-12Nb-4Sn alloy was designed and fabricated for hard tissue replacements. Upon solution treatment followed by water-quenching, the β-type Zr-12Nb-4Sn alloy possesses a combination of low Young's modulus (44 GPa) and low magnetic susceptibility (1.42 × 10 −6  cm 3  g −1 ). An analysis of single-crystal elastic constants and Hill approximation shows that compared with binary β-type Ti-based alloys, the present β-type Zr-12Nb-4Sn alloy exhibits lower bcc-structural (β-phase) stability represented by its slightly lower C′ and much lower C 44 , which gives rise to the ultralow Young's modulus in Zr-12Nb-4Sn alloy. Meanwhile, the low magnetic susceptibility of raw materials, i.e., Zr (1.32 × 10 −6  cm 3  g −1 ), Nb (2.24 × 10 −6  cm 3  g −1 ) and Sn (0.03 × 10 −6  cm 3  g −1 ), leads to the eventual low magnetic susceptibility of Zr-12Nb-4Sn alloy. These results might shed some light on design and development of novel β-type Zr alloys, with a combination of lower Young's modulus and lower magnetic susceptibility, for biomedical applications. [ABSTRACT FROM AUTHOR]

Ordered mesoporous carbon (OMC) has shown great promising as superior support in the creating highly efficient and stable cathodic catalyst for oxygen reduction reaction (ORR) due to its many merits but there are still many challenges. We demonstrate in this work a facile and large-scale strategy to efficiently embed Pt-based crystals within OMC using supercritical carbon dioxide (scCO 2 ) technique. Typically, PtFe/OMC catalysts with the highly dispersive, ultrafine sizes (1.3–2.3 nm), controllable compositions and loadings have been successfully fabricated. Through control of experimental process and loadings, most of crystals can be deposited into mesochannels of OMC. The integration of highly dispersive and ultrafine PtFe crystals as well as high surface area, mesoporous structure and good electrical conductivity of OMC supports make PtFe/OMC promising as active and stable electrocatalysts toward ORR. By careful comparison, PtFe/OMC catalysts show the overwhelmingly better or comparable electrochemical performance compared with previously reported mesoporous carbon supported Pt-based catalysts. These attractive materials hold great potential in cathodic electrocatalyst for fuel cells and the scCO 2 technique is quite superior for constructing OMC with various embedded nanoparticles (such as PtPd, PtCu etc.) [ABSTRACT FROM AUTHOR]

In this work, a binary metastable β-type Ti-41 Nb (wt. %) with a multi-directional Invar effect (i.e., near-zero thermal expansion) was fabricated through the cross-rolling (Cro-R), with an aim to elucidate the relationship between martensitic phase transformation and multi-directional Invar effect. It was found that the Cro-R TiNb alloy shows the Invar effect along the transverse direction (TD) and rolling direction (RD) across a wide temperature range (∼180 K), and the coefficient of thermal expansion (CTE) along the TD and RD are α TD = +0.64 × 10−6 K−1 and α RD = −0.016 × 10−6 K−1, respectively. Further experimental results show that the randomly oriented β parent phase and α″ martensitic phase are distributed in the tiny grains with a high density of dislocations. This high density of dislocations can effectively impede martensitic phase transformation from β to α″ that appears during the subsequent cooling, resulting in the martensitic phase transformation occurring over a wide temperature range. In such cases, the multi-directional Invar effect was achieved via the compensation between the negative thermal expansion (NTE) caused by martensitic phase transformation and the positive thermal expansion (PTE) due to the TiNb matrix lattice vibration during cooling. These experimental results act as a foundation for the design and development of the metastable β-type Ti alloy with a multi-directional Invar effect. • A TiNb alloy with a multi-directional Invar effect was designed and fabricated. • The martensitic phase transformation plays a key role in the multi-directional Invar effect. • The multi-directional Invar effect takes place over a wide temperature range (∼180 K). [ABSTRACT FROM AUTHOR]

A nanocomposite containing three-dimensional (3D) flower-like MoS 2 nanosheets and two-dimensional (2D) interconnected carbon nanosheets was successfully prepared by a facile hydrothermal method. The nanocomposite (MC-2) containing 6% surface-functional carbon nanosheets are beneficial to inhabit the restacking of MoS 2 nanosheets and form curved MoS 2 nanosheets, which are grown along the vertical orientation on the carbon nanosheets. The curved MoS 2 nanosheets could provide more suitable ion transport channels. The carbon nanosheets can enhance the electronic conductivity and keep the integrity of the nanocomposites. MC-2 exhibits the highest specific capacitance of 381 F/g at the current density of 1 A/g, as well as superior cyclic stability with 92% capacitance retention over 3000 cycles in KOH electrolyte. The excellent electrochemical performance of MC-2 as supercapacitor electrode is attributed to the 3D/2D structure and the synergistic effects between MoS 2 nanosheets and carbon nanosheets. [ABSTRACT FROM AUTHOR]

A MoS 2 /CNT nanocomposite containing three-dimensional (3D) flower-like MoS 2 nanospheres and interconnected carbon nanotubes (CNTs) has been successfully synthesized by using MoO 3 and KSCN as reactants and deionized water as solvent with the presence of CNTs through a facile one-step hydrothermal method. The nanocomposite was applied as an electrode material for the supercapacitors with excellent energy storage performance. The structure and morphology of the nanocomposite were characterized by scanning electron microscopy and transmission electron microscopy, which show that MoS 2 nanospheres are about 300 nm in diameter and interconnected by CNTs. The special capacity of the nanocomposites can reach 74.05 F/g at a high current density of 2 A/g, which is higher than those of the flower-like MoS 2 and MoS 2 nanosheets at the same current density. Furthermore, the specific capacitance of the MoS 2 /CNT nanocomposite still maintains 80.8% of initial capacitance over 1000 cycles at the current density of 2 A/g. The excellent electrochemical performance and long cycle life of the nanocomposite are attributed to the synergetic effect between CNTs and ultrathin MoS 2 nanosheets grown vertically on the flower-like MoS 2 . [ABSTRACT FROM AUTHOR]

The effect of long-term isothermal aging of Haynes 230 super-alloy in an advanced ultra-supercritical (A-USC) power plant at 700 °C for up to 10,000 h on microstructural evolution and tensile behavior. And utilizing a combination of the scanning electron microscope (SEM), X-ray diffraction analysis (XRD), and transmission electron microscope (TEM). Although the grain size and grain boundary M23C6 carbides did not change significantly, the dissolution of intercrystallite primary M 6 C carbides and the precipitation of intracrystalline secondary lamellar M 6 C carbides were observed at 2000 h to 10,000 h. According to the SEM and TEM results, it is shown that the dissolution of primary M 6 C carbides makes the W, Mo, and Cr in the γ matrix increase, while the precipitation process of secondary M 6 C carbides is M+ 6 C→M 6 C. To reduce the interfacial energy of the γ matrix, secondary M 6 C carbides are precipitated in the crystal under long-term aging at 700 °C, with a gradual increase in time content. the best tensile and yield strengths at 750 °C occur after 4000 h of aging, with microscopic voids forming mainly around the granular M 6 C carbides in the crystal, but the solid solution strengthening effect of the matrix provides the strength. The worst strength and elongation occur after 10000 h aging, when the dissolution of granular M 6 C and secondary precipitation of M 6 C carbides are most abundant, interfacial cavity formation of granular M 6 C carbides and brittle fracture of M 6 C carbide particles, and the growth of non-co-grained secondary M 6 C carbides with the matrix allow more microscopic cavities to appear during high-temperature tension, reducing the strength of Haynes 230 and plasticity. • Phase precipitation behavior of Haynes 230 was investigated during long-term aging at 700 ℃. • Precipitation processes of secondary lamellar-like M 6 C carbide were clarified. • Dissolution of primary granular M 6 C carbides was discussed. • Variation in mechanical properties is divided into several stages. • The relationship between precipitation processes and mechanical properties was established. [ABSTRACT FROM AUTHOR]

Mn 3 Zn 0.5 Sn 0.5 N/Cu composites were successfully prepared by sintering at 723 K and 823 K. The results show that the thermal expansion of Cu decreases effectively by mixing Mn 3 Zn 0.5 Sn 0.5 N within its negative thermal expansion temperature range. The thermal expansion of composites can be tailored by adjusting the volume fraction of Mn 3 Zn 0.5 Sn 0.5 N. When the volume fraction of Mn 3 Zn 0.5 Sn 0.5 N is 40%, the composite shows a near zero thermal expansion, with the coefficient of thermal expansion of 0.268 × 10 −6 K –1 Mn 3 Zn 0.5 Sn 0.5 N/Cu composites exhibit excellent electrical conductivity at the level of 10 4 S/cm, which is less than that of the matrix Cu. The hardness of composite is improved by adding Mn 3 Zn 0.5 Sn 0.5 N with high stiffness. Some classic models are used to predict the properties of composites and corrected according to the experiment data. [ABSTRACT FROM AUTHOR]

Multi-pass isothermal continuous hot deformation experiments were designed for homogenization and recrystallization in the as-cast alumina-forming austenite (AFA) heat-resistant alloy. Flow curves and microstructure characterization were used to study the grain evolution with different deformation parameters in each pass. In particular, attention was paid to the dendrites and segregated phase. Under different hot deformation conditions, the alloys show significant work-hardening characteristics, which result from the strengthening effect of the primary segregated MC-type carbide. The increase in deformation temperature contributes significantly to dynamic recrystallization (DRX), and the main mechanism of DRX is discontinuous DRX (DDRX). The continuous DRX (CDRX) is less occurring. Static recrystallization (SRX) occurs during the isothermal holding time between deformation passes. SRX becomes more and more apparent with temperature and the holding time. The increase in the deformation passes leads to a gradual disappearance of the alloy dendrites and an increase in the recrystallization volume fraction. Meanwhile, the segregated phase gradually decomposes into particles and partially dissolves. However, the segregated phase particles eventually show band-like distribution. SRX grains around the segregated phase will exhibit similar orientations due to particle-stimulated nucleation (PSN) mechanisms. Until the grain size increases to the point that it can escape from particle restraint, it will transform to random orientation. The above study confirms that multi-pass isothermal continuous hot deformation can improve the as-cast microstructure and guide practical industrial production. • The isothermal multi-pass hot deformation promotes recrystallization and segregated phase dissolution in as-cast AFA alloy. • MC-type primary carbide segregated phase is partially dissolved, the remaining particles are distributed as bands. • DDRX is the dominant dynamic recrystallization mechanism, with CDRX playing a lesser role. • Static recrystallized grains will have approximate orientation due to the particle-stimulated nucleation mechanism. [ABSTRACT FROM AUTHOR]

Highlights: [•] Alkaline-earth metal titante AETiO3 doped CCTO ceramics were prepared. [•] All the samples show a strong nonlinear relationship between E and J. [•] Good frequency stability can be observed in the samples. [•] The best-reported dielectric loss value of CCTO ceramic of 0.0243 was obtained. [ABSTRACT FROM AUTHOR]

Abstract: Zn-substituted CaCu3Ti4O12 ceramics were prepared by the sol–gel method. Their microstructures and electrical properties were investigated. XRD patterns showed that the CaCu3− x Zn x Ti4O12 (CCZTO) (x =0.00, 0.06, 0.10, 0.20) ceramics, after sintering at 1050°C for 20h, were single phase with no Cu-rich phase. SEM results indicated that the samples had smaller grain sizes than those synthesized by traditional solid-state reaction methods. The dielectric and varistor properties of CCZTO were analyzed by a precision impedance analyzer and a varistor tester, respectively. According to Debye''s equation, which states that the smaller the leakage current, the smaller the dielectric loss will be in the low-frequency region, we were able to roughly predict the relative value of the dielectric loss at low frequency by the leakage current. The best overall properties were obtained for x =0.06 (CaCu2.94Zn0.06Ti4O12), which has several prospective applications, such as low voltage varistor switchings, gas-sensing devices, and varistor–capacitor double property devices. [Copyright &y& Elsevier]

Abstract: CdSe particles with wurtzite structure have been synthesized via solvothermal method using a mixed solution of triethylenetetramine (TETA) and de-ionized water (DIW). It was found that ball-like CdSe precursor with zinc-blende phase could be transformed to wurtzite structure after heat-treating at 580°C in Ar atmosphere and the obtained microspheres were made up of many nanometer sized CdSe particles. The experimental results were compared with CdSe obtained via hydrothermal method using N2H4·H2O as the reducing agent and it was found that CdSe nanorods with wurtzite structure were obtained. It was speculated that TETA in the mixed solution played the role of reducing agent and surfactant. Both the as-prepared products and the annealed powders were systematically characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared absorbance spectroscopy (FTIR) and thermogravimetric analysis (TGA). [Copyright &y& Elsevier]

Abstract: ZrW2O8 powders were prepared by hydrothermal thermal method using sodium dodecyl benzene sulfonate (SDBS) as surfactant. The products were investigated by X-ray diffraction (XRD) method, scanning electron microscopy (SEM), thermogravimetric and differential scanning calorimetry (TG–DSC) and Fourier transform infrared (FTIR) absorption spectra. Results indicate that the resulting powders are single cubic phase with high crystallinity. With increasing the amount of SDBS, morphology and particle size change from rod-like with an average dimension of 1.2μm×1.2μm×10μm to layered column with an average diameter of 0.4μm. ZrW2O8 powders exhibit negative thermal expansion property. And the amount of SDBS is not influence on the average thermal expansion coefficients. The thermal expansion coefficients are about similar with an average value of −5.8×10−6 °C−1 from room temperature to 500°C. However, the morphology has some effect on the thermal expansion coefficient of α-ZrW2O8. [Copyright &y& Elsevier]

Abstract: The interface structures of the (Al2O3 +Al3Zr)/A356 nanocomposites fabricated by magneto-chemistry in situ reaction are investigated by TEM technologies. The results indicate that the Al3Zr/Al, Al2O3/Al and Al2O3/Si interfaces are net and smooth, no interface reactants are observed. The vector relations for Al3Zr and α-Al phases are: , , and , for α-Al2O3 and Si phases. The misfit degree δ for the (0001) crystal plane of the α-Al2O3 phase and the (110) crystal plane of the Si phase is 5.08%. The interface fit-relations for the Al2O3 phase and the Si phase are that the Si phase can be nucleated on theα-Al2O3 phase. These contribute to the perfect properties of the nanocomposites. [Copyright &y& Elsevier]

Abstract: The (Al2O3 +Al3Zr)/A356 nanocomposites are fabricated via magnetochemistry in situ reaction. The interface between the in situ particles and the aluminum matrix, the mechanical properties and behaviors are investigated by SEM, TEM and in situ tensile observations. The results indicate that the interfaces are net and no interfacial outgrowth observed; the values of the tensile strength, yield strength and the Brinell Hardness are reached 393.8MPa, 339.74MPa and 139.8kgf/mm2, respectively with the pulsed magnetic field assistance; the cracks are initiated by the dislocation accumulation effects, the cavity-nucleation effects and the matrix flaw effects; the crack growth behaviors are very much dependent on the microstructure of the composites. The fracture model of the composites is established and discussed. [Copyright &y& Elsevier]

• The Avrami kinetics model of the Fe-Cr-Ni-Al-Nb superalloy was constructed, which revealed the three stages of DRX, including nucleation, grain growth and grain contact. • Twin boundaries were found in the DRX grains under the strain of 0.3, which would consume the stored energy, thus inhibiting the growth of grains. • The generation of ∑3 derived from "growth accents" during hot deformation. • The twins found near the original grain boundaries could promote the bulging behavior and accelerate the separation of the bulged sites from the matrix, which was beneficial for DRX. • Three different DRX mechanisms were identified. DDRX was found the dominant nucleation mechanism, while CDRX and TDRX were evidenced as the auxiliary mechanism. Thermal-mechanical experiments of a newly developed Fe-Cr-Ni-Al-Nb superalloy were conducted on a Gleeble simulator under the temperature of 900–1100 ℃ and the strain rate of 0.01–5 s−1. The microstructure evolution and the nucleation mechanisms of dynamic recrystallization (DRX) were characterized by electron backscattering diffraction (EBSD) technique, and the results showed that relatively higher temperature, lower strain rate and larger true strain were favorable for DRX. When the superalloy was deformed under 1050 ℃− 0.1 s−1, nearly complete DRX occurred with the power dissipation efficiency of 0.34. Moreover, the Avrami dynamic model of the investigated superalloy was constructed, which suggested that there were three stages during DRX, including nucleation, grain growth and grain contact. Furthermore, three different DRX mechanisms during hot deformation were identified. The bulge and nucleation characteristics of original grain boundaries occurred within all experimental parameters, confirmed that discontinuous dynamic recrystallization (DDRX) was the main DRX mechanism. Besides, the presence of a small amount of medium angle grain boundaries affirmed that subgrains continuously rotated and absorbed dislocations during deformation, meaning that the continuous dynamic recrystallization (CDRX) was an auxiliary nucleation mechanism. Moreover, annealing twins, appeared in the matrix, provided additional nucleation sites for DDRX and CDRX, encouraging the twinning dynamic recrystallization (TDRX), which effectively promoted the progress of DRX. [ABSTRACT FROM AUTHOR]

Bimetallic silver–iron nanoparticles (Ag–Fe NPs) are an attractive antimicrobial material because of their multifunctional properties. The antimicrobial performance of Ag–Fe NPs is affected significantly by alloying structure, particle size and composition, but the preparation is a challenge due to the large difference in lattice constants of the two elements. An ultrasonic-assisted in situ reduction method was used here to prepare Ag–Fe/graphene-based cellular monolith (Ag–Fe/GCM) materials with well-defined alloy structure, ultrafine size and abundant hierarchical structure. We found that the antimicrobial activity of such materials decreased but the stability of Ag improved with the increase of Fe content within a certain range. The more active Fe in alloys can protect the Ag from oxidation, which reduces the release of Ag+. However, the release of Fe ions led to more generation of reactive oxygen species compared with Ag/GCM, which maintained a high antibacterial activity. By adjusting Fe content, an Ag–Fe/GCM material with optimal performance was achieved. This work not only provides a method for preparing Ag–Fe alloys but is also useful for understanding its antimicrobial mechanism. Moreover, Ag–Fe/GCM material also performs well in filtering of bacterial pathogens, and is a highly promising material for advanced antimicrobial and water-treatment applications. Image 1 • Developing the synthetic approach for ultrafine Ag–Fe/GCM antibacterial materials. • The MIC 100% and MBC 100% are 80 ppm and 50 ppm towards E. coli , and 100 ppm and 80 ppm towards S. aureus. • It has good biocompatibility, stability, and performs well in filtering of bacterial pathogens. • Investigating the mechanism of biological performance of Ag–Fe/GCM based on Ag–Fe alloy structure. [ABSTRACT FROM AUTHOR]

Abstract: Great efforts have been made to fabricate ZnO nanostructures/films due to their wide-field applications. In this report, ZnO nanorods/films have been prepared by a low-temperature solution growth. The combined effects of aluminum ion and solvent on the growth of ZnO nanorods/films have been investigated. The density of ZnO nanorods grown in the aqueous solution deceases with increasing concentration of Al3+, while it increases with increasing ethanol content in the solution. The SEM results clearly indicate that there is a competition between solvent and Al3+ ion effects on the nucleation density, owing to the lateral growth of ZnO crystals with ethanol and the formation of a second compound of zinc aluminum layered double hydroxide, respectively. [ABSTRACT FROM AUTHOR]