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ABSTRACTIn this work, by using multi-scale characterizations from electron channeling contrast imaging (ECCI) to atom probe tomography (APT), we directly evidenced that the massive cracking events in the selective-laser-melted (SLMed) Haynes 230 superalloy are due to the continuous decoration of an M23C6-type thin film at grain boundaries. The high-melting-point nature of the carbide rules out the possibility of liquidation cracking, while the long and straight film surface facilitates stress-induced solid-state cracking. Impurities, Si, Mn and Fe, greatly enhance the cracking susceptibility despite the interesting fact that they are strongly depleted from the carbide.

Surface modified nano-flake Cu powder was prepared by plasma assisted ball milling by adding stearic acid as a process agent and its tribological properties were tested. The results indicate that the Cu particle exhibiting an excellent superplasticity has severe plastic deformation induced by a synergistic effect of plasma high-rate heating and electroplasticity, and the 20nm-thick flake-like Cu particles are obtained after 5h milling time of plasma milling. These nano-flake Cu particles owning oleophobicity characteristics exhibit good dispersion in the 40CA marine lubricating oil due to that the surface of Cu nano-flake adsorbs and chemically bonds with some non-polar groups under the plasma assisted ball milling with stearic acid. The severe deformation of the nano-flake Cu particles displaying high activation are easily adsorbed and spread on the surface of the friction counterpart in the process of sliding, which promotes a better wear resistance for compound lubricant with nano-flake Cu addition. Under a high rotating speed and excessive load, the nano-flake Cu powder provides excellent friction-reducing and self-repairing characters and improves the anti-wear performance under an extreme pressure condition.

Gradient structures were introduced via torsional treatment to Cu and CuAl alloys with different starting grain sizes and stacking fault energies (SFEs). Systematic investigations showed that the original grain sizes and SFEs of these materials play vital roles in affecting the formation of gradient structures and their corresponding mechanical properties. Large grain size and relatively low SFE are two critical requirements for the formation of the optimum gradient structure. A superior combination of high strength and good ductility can be achieved by torsional treatment in ultra-coarse-grained materials with low SFEs, which is attributed to the hierarchical structures that led to the simultaneous activations of different deformation mechanisms from full dislocation activities to partial dislocation slip and nano-twinning along the radial direction. Keywords: Gradient structure, Strength, Ductility, Twinning, Stacking fault energy

Mechanical properties and microstructural evolution of Cu-10wt.%Zn and Cu-30wt.%Zn alloys after pre-torsional deformation have been investigated in this study. The results indicated that pre-torsional deformation can significantly enhance the strength of both Cu-10wt.%Zn and Cu-30wt.%Zn alloys without changing their shape and size, but with the sacrifice of the ductility. The pre-torsion deformation can introduce gradient hardness and microstructures along the radial direction, with the microstructures along the radial direction in Cu-30wt.%Zn alloy being "dislocations→stacking faults→twins (low density)". The stacking fault energy affects significantly the microstructure along the radial direction.

Beta-Al2O3 precursor powders were synthesized by glycine-nitrate combustion at a low temperature using metal nitrate and GNP as raw materials. The thermal decomposition mechanism of the gel and the formation process of beta-Al2O3 were investigated by XRD, TG/DSC, SEM, NMR and EIS. The results show that beta-Al2O3 precursor powder with the average size of 42.0nm can be obtained at 1150℃, 150℃ lower than the solid state reaction. The precursor powder has good forming and sintering performance. The sample is calcined at 1620℃, then the Al(Ⅳ) and the Al(Ⅵ) in the structure of the sample is around δ=45 and δ=-6, respectively. The relative density of the sample is 97.6%. The ionic conductivity at 350℃ is 0.046S·cm-1.

Abstract Carbon nanofibers containing linear mesocage arrays were prepared via evaporation induced self-assembly method within AAO template with an average channel diameter of about 25 nm. The TEM results show that the mesocages have an elongated shape in the transversal direction. The results of N2 adsorption–desorption analysis indicate that the sample possesses a cage-like mesoporous structure and the average mesopore size of the sample is about 18 nm.

Abstract Three-dimensional cubic ordered mesoporous carbons with tunable pore sizes have been synthesized by using cubic Ia3d mesoporous KIT-6 silica as the hard template and boric acid as the pore expanding agent. The prepared ordered mesoporous carbons were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption–desorption analysis. The results show that the pore sizes of the prepared ordered mesoporous carbons with three-dimensional cubic structure can be regulated in the range of 3.9–9.4 nm. A simplified model was proposed to analyze the tailored pore sizes of the prepared ordered mesoporous carbons on the basis of the structural parameters of the silica template.

Abstract Mesoporous silica nanofibers were synthesized within the pores of the anodic aluminum oxide template using a simple sol–gel method. Transmission electron microscopy investigation indicated that the concentration of the structure-directing agent (EO20PO70EO20) had a significant impact on the mesostructure of mesoporous silica nanofibers. Samples with alignment of nanochannels along the axis of mesoporous silica nanofibers could be formed under the P123 concentration of 0.15 mg/mL. When the P123 concentration increased to 0.3 mg/mL, samples with a circular lamellar mesostructure could be obtained. The mechanism for the effect of the P123 concentration on the mesostructure of mesoporous silica nanofibres was proposed and discussed.

Abstract Zinc hydroxide fluoride (Zn(OH)F) with novel flower-like morphology has been prepared via a microwave-assisted ionic liquid route. The flower-like Zn(OH)F particle has six petals and every petal is composed of lots of acicular nano-structure. Nanoporous ZnO is obtained by thermal decomposition of as-prepared Zn(OH)F in air, and the flower-like morphology is well retained. In the process of synthesis, ionic liquid 1-Butyl-3-methylimidazolium tetrafluoroborate is used as both the reactant and the template.

New high-efficiency blue-light-emitting phosphorescent devices with 300 Å-thick emissive layer of N,N′-dicarbazolyl-3,5-benzene [mCP] doped with 10 vol.% bis[(3,5-difluoro-4-cyanophenyl)pyridine]iridium picolinate [FCNIr(pic)] were fabricated with the different treatments of hole and electron transport layers. In the experiments, a single layer of 1,1-bis-(di-4-polyaminophenyl)cyclohexane [TAPC] and a double layer of N,N′-di(1-naphthyl)-N,N′-diphenylbenzidine [NPB] and mCP were used as hole transport layers (HTLs). In addition, 500 Å-thick double layers of tris-[3-(3-pyridyl)mesityl]borane [3TPYMB] and 4,7-diphenyl-1,10-phenanthroline [Bphen] were used as electron transport layers (ETLs) with various thickness combination of 3TPYMB/Bphen. Among the fabricated devices, the one using TAPC as an HTL and 3TPYMB(100 Å)/Bphen(400 Å) as an ETL showed best electroluminescent characteristics with a maximum quantum efficiency of 13.3% and a luminance of 950 cd/m2 at 10 V. The color coordinates were (0.14, 0.22) on the Commission Internationale de I'Eclairage (CIE) chart, and the electroluminescent spectra showed the double-peak emissions at 458 nm and 483 nm.