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Detailed characterizations of interfacial dislocation networks in a nickel-base single crystal superalloy after creep loading for 85 h at 1100 °Cand 130 MPa were carried out at larger magnifications. The “square-like” dislocation network is formed by dislocation reaction including a[010], a/2[110], a / 2 [ 1 1 ¯ 0 ] dislocations and is different from square (and hexagonal) networks in formation mechanism and geometric structure. The atomic structure of core region of dislocations indicates their individual features and highlights the three-dimensional geometry of “square-like” dislocation network for the first time. [ABSTRACT FROM AUTHOR]

At present, the development of electromagnetic wave absorption (EWA) materials is of great significance with the rapid development of electronic products. Based on the adjustable mechanical and electromagnetic properties of epoxy (EP)-based composite materials, research in the field of EWA has been continuously expanded. This review summarized recent developments of EP-based composites for their applications in EWA and classified composite materials according to the coating order and mixing ratio. In addition, the mechanisms of EWA were also introduced, including dielectric loss and magnetic loss. Finally, current challenges and opportunities for the development of EP-based EWA materials were proposed and the future development trend was pointed out. [ABSTRACT FROM AUTHOR]

The partitioning behaviors of alloying elements Cr, Co, Al, Ta, etc. on the γ and γ′ phases of high Cr-containing (∼9wt.%) nickel-base single crystal superalloys have been investigated with and without the addition of 3wt.% Ru. The “reverse partitioning effect” occurs, which means that the addition of Ru causes the partition of Cr and Co into γ′ phase, while Al an Ta concentrate into γ matrix. However, Ru promotes the precipitation of topologically close-packed (TCP) phases, since the diffusion coefficient between the TCP phase and the matrix interface increases with the diffusion behaviors of refractory elements. For the coarsening and slightly rafting of γ′ phases, the increase of elemental diffusion plays much more important role in its kinetic process than the decrease of lattice misfit. [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: By means of high resolution transmission electron microscopy (HRTEM) and high-angle annular dark-field image technique (HAADF), morphological of plate-shaped σ phase and interfacial characteristics between plate-shaped σ phase and γ phase in Ni-based single crystal superalloys have been studied. On the basis of HRTEM observations, an atomic structural interface between σ phase and γ phase with a step has been proposed. σ Phase has the relationship of [001]γ//[11 ]σ, ( 20)γ//( 10)σ, ( 0)γ//(111)σ; [011]γ//[110]σ, (1 1)γ//(00 )σ with the γ phase. The compositional characteristics of the σ phase which are rich in more heavy elements, such as W, Re, Cr and Ru, has also been clearly revealed by the HAADF imaging technique and Energy Dispersive X-Ray Spectroscopy (EDS) mapping analysis. [Copyright &y& Elsevier]

Abstract The internal characteristics of the μ phase in Ni-base single crystal superalloys aged at 1100 °C for 1000 h were investigated via spherical aberration-corrected transmission electron microscopy. There were a large number of planar defects on the (001) plane at the growth tip of the μ phase. HAADF-STEM results show that these planar defects were mainly of two types. 1) A twin structure with a mirror plane of the middle atomic planes of the Zr 4 Al 3 sheet, which was generated by shearing of atoms in the MgCu 2 sheet along the [1-10] direction. 2) A mirror-symmetrical stacking fault of two Zr 4 Al 3 sheets, which was formed by the pulling out of a single MgCu 2 sheet. The planar defects were mainly caused by coordination of the distortions of the μ phase and the matrix. Segregation of Mo, Cr, and Re elements occurred near stacking faults, rather than twin structures. Highlights • There are a large number of planar defects on the (001) plane at the growth tip of the lath-like μ phase. • The twin structure in μ phase is generated by shearing the atoms of MgCu 2 sheet along the [1−10] direction. • The stacking fault in μ phase is a mirror-symmetrical of two Zr 4 Al 3 sheets, which is formed by pulling out one MgCu 2 sheet. [ABSTRACT FROM AUTHOR]

Misfit dislocation structures are investigated in a nickel-based single crystal superalloy subjected to 38.8 h creep at 1100 °C and 130 MPa using conventional and high resolution transmission electron microscopy (HRTEM). The misfit dislocation was identified as an uncommon one with Burgers vector b = a/2 [ 2 ¯ 11 ] , which can be described as inserting (or extracting) one ( 1 1 ¯ 1 ) half plane and one ( 11 1 ¯ ) half plane. This dislocation was decomposed into two partial dislocations b 1 and b 2 , with b 1  = a/2 [ 1 ¯ 01 ] and b 2  = a/2 [ 1 ¯ 10 ] . Partial dislocations b 1 and b 2 were arranged in a “V” shape, connected by the antiphase boundary (APB), which could hinder the dislocation motion to achieve the effect of dislocation enhancement. [ABSTRACT FROM AUTHOR]

The nickel based superalloy GH4037 is employed in gas turbine blades because of its high temperature strength and oxidation resistance. Microstructural evolution and deformation features in gas turbine blades after 1600 h service have been investigated by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The microstructure of blade changes according to complex and comprehensive temperature and stress fields applied on it. Microstructural observations show that minor carbide precipitates dispersedly precipitate in the matrix. Two MC decomposition reactions occur: MC + γ → M 23 C 6 + γ′ and MC + γ → M 23 C 6 + η. Blocky, closely spaced M 23 C 6 particles continuously distribute along grain boundaries. The main deformation features, such as slip bands, APB-coupled dislocation pairs, stacking faults bound by partial dislocations and deformation twinning, have also been analyzed in terms of fundamental deformation mechanisms and environmental effects. [ABSTRACT FROM AUTHOR]

• Heterostructured g-C 3 N 4 /Ti 3 C 2 T x endows electrode with enhanced structural stability and fast charge transfer. • The heterostructured g-C 3 N 4 /Ti 3 C 2 T x delivers superior aluminum-storage performance. • The charge-discharge mechanism for g-C 3 N 4 /Ti 3 C 2 T x is reversible intercalation of chloroaluminate anions. [Display omitted] As a compelling complement to lithium batteries, rechargeable aluminum batteries (RABs) have attracted considerable attention because of abundant natural resources, high volumetric capacity, and safety property of aluminum metal. However, the deployment of RABs is hampered by the lack of favorable cathodes with high capacity and rapid kinetics. To address the long-unresolved issue of aluminum-storage capacity and rate, here we design a heterostructured g-C 3 N 4 /Ti 3 C 2 T x hybrid which offers a conductive supporting framework to maintain structural integrity and accelerate electronic transport. The energy storage mechanism of the heterostructured g-C 3 N 4 /Ti 3 C 2 T x cathode was demonstrated as the reversible intercalation of AlCl 4 − during cycling. Moreover, the battery-capacitance model mechanism in the heterostructured g-C 3 N 4 /Ti 3 C 2 T x hybrids may accelerate the kinetics of the electrode reactions. Furthermore, DFT calculations certify that heterostructured g-C 3 N 4 /Ti 3 C 2 T x possesses enhanced electrical conductivity and Al trapping capability. Accordingly, the heterostructured g-C 3 N 4 /Ti 3 C 2 T x cathode affords RABs with an excellent Al-storage property (237 mAh g-1 at 0.5 A g-1) and considerable rate capabilities (174 mAh g-1 at 4 A g-1) among state-of-the-art cathode materials for aluminum batteries. [ABSTRACT FROM AUTHOR]

Highlights: [•] Critical resolved shear stress for twinning in superalloy are calculated theoretically. [•] Finite element method analyzes the stress distribution around micropore near crack-tip. [•] Deformation twinning occurs due to the stress concentration. [ABSTRACT FROM AUTHOR]

Abstract: In situ nanostructured ceramic matrix composite coating was prepared by reactive plasma spraying micro-sized Al–Fe2O3 composite powders. The microstructure of the composite coating was characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy, respectively. The results indicated that the composite coating exhibited dense and crack-free microstructure with a number of spherical α-Fe and γ-Al2O3 nano-grains embedded within equiaxed and columnar FeAl2O4 nano-grains matrix. The composite coating showed markedly higher toughness and wear resistance than the conventional Al2O3 coating. [ABSTRACT FROM AUTHOR]