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The enhanced mechanical properties of Ni-based single-crystal superalloys induced by refractory elements such as Re, Wo, Mo, etc. are essential for the manufacture of advanced aero engines' turbine blades. Whereas these elements could promote the formation of the topologically close-packed (TCP) phases, and their growth would have a deleterious effect on the creep rupture life of single-crystal superalloys. Concomitantly, the formation of the brittle phase of the internal nitrides, especially the aluminium nitride (AlN), would be detrimental to superalloys as well. Nonetheless, the formation relationship between AlN and TCP phases has maintained opaque. In this study, the relationship between the TCP phase and AlN phase was analysed by microscopic methods, such as BSE, TEM and EDS. An AlN phase located near the TCP phase in the deep surface of the superalloy was found, and its formation was suggested to be related to nitrogen penetration during the thermal exposure. This accompanying growth of the AlN phase and TCP phase in the deep surface could provide a new perspective on the formation mechanism of these brittle phases in the Ni-based single-crystal superalloys. [ABSTRACT FROM AUTHOR]

Abstract It is very challenging to synthesize perovskite oxides with controlled morphology and defect states at the same time. In this work, the BaZrO 3 hollow nanostructures with oxygen vacancies were facilely synthesized through one-step solvothermal method using ethylenediamine (EDA) as solvent. The as-synthesized BaZrO 3 could split pure water into H 2 without addition of sacrificial agent under UV light irradiation. The photocatalytic H 2 production rate is about 15 times than that of the commercial BaZrO 3 (BZO-C). It is believed that the presence of oxygen vacancies and the hollow morphology made contribution to the improvement of photocatalytic performance. This work provides a reference for microstructure and defect modification of photocatalysts at the same time to enhance the photocatalytic performance. Highlights • The BaZrO 3 with hollow structures and oxygen defects was one-step synthesized. • The as-obtained BaZrO 3 shows increased photocatalytic activities in pure water. • The special morphology and defects contribute to the improvement of properties. • The hollow structures and defects result from the presence of EDA in the reaction. • This work provides a reference for microstructure and defect modification. [ABSTRACT FROM AUTHOR]

Here, we investigate a new type of kink structure that is found at γ/γ′ interfaces in nickel-based single crystal superalloys. We studied these structures at the atomic and elemental level using aberration corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The core of the dislocation absorbs high-Z elements (i.e., Co and Re) that adopt hexagonal arrangements, and it extrudes elements (i.e., Ni and Al) that adopt face centered cubic (fcc) structures. High-Z elements (i.e., Ta and W) and Cr, which is a low-Z element, are stabilized in body centered cubic (bcc) arrangements; Cr tends to behave like Re. High-Z elements, which migrate and adopt a hexagonal structure, induce kink formation at γ/γ′ interfaces. This process must be analyzed to fully understand the kinetics and dynamics of creep in nickel-based single crystal superalloys. [ABSTRACT FROM AUTHOR]

Abstract: A novel flat-peach-like ZnO has been synthesized by hydrothermal method. The obtained ZnO is twined flat-peach-like structure with about 4μm in diameter and 2μm in thickness, which is a new member of the ZnO family. XRD, TEM, SEM, RS, SAED, EDX and Photocurrent spectra are employed to characterize the crystal phase, morphologies, the chemical compositions, and photocurrent properties of the ZnO microstructure. The experimental results show the as-prepared ZnO is single-crystalline structure and the reaction time plays a key role in modulating the morphology of ZnO. And the growth mechanism of ZnO is tentatively investigated. Furthermore, the flat-peach-like ZnO exhibits larger photocurrent intensity than the plate-like one in the 300–450nm region. [Copyright &y& Elsevier]

Abstract: Nanostructured Gd0.1Ce0.9O1.95 (GDC)-impregnated La0.7Ca0.3CrO3−δ (LCC) composites were investigated as symmetrical electrodes for La0.9Sr0.1Ga0.8Mg0.2O3−δ (LSGM)-supported solid oxide fuel cells (SOFCs) without using interlayer at anode/electrolyte interface. The impregnation of aqueous Gd0.1Ce0.9(NO3)x solution into the porous LCC electrode backbones was found to form nanosized GDC particles on LCC surfaces after calcining at 850 °C for 30 min. The optimized performance of electrodes for SOFCs had been achieved through the impregnation cycles of 3–7 times. The introduction of the ion conducting phase GDC in nanometer significantly enhanced the symmetrical electrode performance. The symmetrical cell with the impregnation of five times displayed the best performance and the maximum power densities were 521 mW cm−2 and 638 mW cm−2 at 850 °C and 900 °C with dry H2 as fuel, respectively. Using commercial city gas containing H2S as fuel, the maximum power densities of the cell reached 362 mW cm−2 and 491 mW cm−2 at 850 °C and 900 °C, respectively. The microstructure, valence state of Ce element and electrochemical stability of the nanostructured GDC-impregnated LCC composites were also discussed. [Copyright &y& Elsevier]