High Resolution Sem Fractography of Te-Embrittled Hastelloy-N

1976 ◽  
Vol 34 ◽  
pp. 458-459
Author(s):  
D. N. Braski
Keyword(s):  
High Resolution ◽  
Grain Boundary ◽  
Molten Salt ◽  
Room Temperature ◽  
Development Program ◽  
Alloy Development ◽  
Fission Process ◽  
X Ray ◽  
Grain Boundary Embrittlement ◽  
Alloy Development Program

Hastelloy-N (16%Mo-7%Cr-4%Fe-0.55%Mn-0.06%C-bal Ni) has long been a leading candidate material for a molten salt reactor. However, it was recently discovered that small amounts of Te, created by the fission process, caused grain boundary embrittlement in the structural material. Consequently, an alloy development program at this laboratory has directed considerable efforts towards modification of Hastelloy-N to improve its resistance to Te embrittlement and still retain excellent resistance to radiation damage. In this investigation, a JEOL 100C TEM with an energy dispersive x-ray spectrometer (EDX) and high resolution (50 Å) SEM attachments have been used to characterize the grain boundary surfaces of various Hastelloy-N alloys embrittled by Te.Samples of Hastelloy-N were exposed to the tellurium source, Cr3Te4, in a molten salt (LiF + BeF2 + ThF4) or to the vapor above Cr3Te4 in a closed quartz system. All corrosion tests were at 700°C. The samples were subsequently tensile tested to failure at room temperature.

The crystal structures of solvent-free alkali-metal squarates from powder diffraction data

2005 ◽  
Vol 220 (11) ◽  
Author(s):  
Robert E. Dinnebier ◽  
Hanne Nuss ◽  
Martin Jansen
Keyword(s):  
High Resolution ◽  
Alkali Metal ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Room Temperature ◽  
Solvent Free ◽  
Crystallographic Data ◽  
Powder Diffraction Data ◽  
X Ray

AbstractThe crystal structures of solvent-free lithium, sodium, rubidium, and cesium squarates have been determined from high resolution synchrotron and X-ray laboratory powder patterns. Crystallographic data at room temperature of Li

scholarly journals High-resolution neutron and X-ray diffraction room-temperature studies of an H-FABP–oleic acid complex: study of the internal water cluster and ligand binding by a transferred multipolar electron-density distribution

IUCrJ ◽  
2016 ◽  
Vol 3 (2) ◽  
pp. 115-126 ◽  
Author(s):  
E. I. Howard ◽  
B. Guillot ◽  
M. P. Blakeley ◽  
M. Haertlein ◽  
M. Moulin ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Fatty Acid ◽  
High Resolution ◽  
Density Distribution ◽  
Electron Density ◽  
Electron Density Distribution ◽  
Room Temperature ◽  
Water Molecules ◽  
X Ray

Crystal diffraction data of heart fatty acid binding protein (H-FABP) in complex with oleic acid were measured at room temperature with high-resolution X-ray and neutron protein crystallography (0.98 and 1.90 Å resolution, respectively). These data provided very detailed information about the cluster of water molecules and the bound oleic acid in the H-FABP large internal cavity. The jointly refined X-ray/neutron structure of H-FABP was complemented by a transferred multipolar electron-density distribution using the parameters of the ELMAMII library. The resulting electron density allowed a precise determination of the electrostatic potential in the fatty acid (FA) binding pocket. Bader's quantum theory of atoms in molecules was then used to study interactions involving the internal water molecules, the FA and the protein. This approach showed H...H contacts of the FA with highly conserved hydrophobic residues known to play a role in the stabilization of long-chain FAs in the binding cavity. The determination of water hydrogen (deuterium) positions allowed the analysis of the orientation and electrostatic properties of the water molecules in the very ordered cluster. As a result, a significant alignment of the permanent dipoles of the water molecules with the protein electrostatic field was observed. This can be related to the dielectric properties of hydration layers around proteins, where the shielding of electrostatic interactions depends directly on the rotational degrees of freedom of the water molecules in the interface.

scholarly journals Experimental Investigations of the Interaction of SO2 with MgO

1999 ◽  
Vol 590 ◽  
Author(s):  
Andrea Freitag ◽  
J. A. Rodriguez ◽  
J. Z. Larese
Keyword(s):  
High Resolution ◽  
Film Thickness ◽  
Room Temperature ◽  
Temperature Programmed Desorption ◽  
Experimental Investigations ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Temperature Programmed ◽  
X Ray Absorption

ABSTRACTHigh resolution adsorption isotherms, temperature programmed desorption (TPD), x-ray diffraction (XRD) and x-ray absorption near edge spectroscopy (XANES) methods were used to investigate the interaction of SO2 with high quality MgO powders. The results of these investigations indicate that when SO2 is deposited on MgO in monolayer quantities at temperatures near 100K both SO3 and SO4 species form that are not removed by simply pumping on the pre-dosed samples at room temperature. TPD and XANES studies indicate that heating of pre-dosed MgO samples to temperatures above 350 °C is required for full removal of the SO3/SO4 species. XANES measurements made as a function of film thickness indicate for coverages near monolayer completion that the SO4 species form first.

scholarly journals Neutron and high-resolution room-temperature X-ray data collection from crystallized lytic polysaccharide monooxygenase

2015 ◽  
Vol 71 (11) ◽  
pp. 1448-1452 ◽  
Author(s):  
John-Paul Bacik ◽  
Sophanit Mekasha ◽  
Zarah Forsberg ◽  
Andrey Kovalevsky ◽  
Jay C. Nix ◽  
...  
Keyword(s):  
High Resolution ◽  
Diffraction Data ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Lytic Polysaccharide Monooxygenase ◽  
Data Set ◽  
X Ray ◽  
Processing Enzymes ◽  
Bacteria And Fungi ◽  
Polysaccharide Monooxygenase

Bacteria and fungi express lytic polysaccharide monooxgyenase (LPMO) enzymes that act in conjunction with canonical hydrolytic sugar-processing enzymes to rapidly convert polysaccharides such as chitin, cellulose and starch to single monosaccharide products. In order to gain a better understanding of the structure and oxidative mechanism of these enzymes, large crystals (1–3 mm3) of a chitin-processing LPMO from the Gram-positive soil bacteriumJonesia denitrificanswere grown and screened for their ability to diffract neutrons. In addition to the collection of neutron diffraction data, which were processed to 2.1 Å resolution, a high-resolution room-temperature X-ray diffraction data set was collected and processed to 1.1 Å resolution in space groupP212121. To our knowledge, this work marks the first successful neutron crystallographic experiment on an LPMO. Joint X-ray/neutron refinement of the resulting data will reveal new details of the structure and mechanism of this recently discovered class of enzymes.

Design of 2D-nanocrystals in water: preparation, structure and functionalization

2018 ◽  
Vol 90 (5) ◽  
pp. 833-844
Author(s):  
Leonid Aslanov ◽  
Valery Zakharov ◽  
Ksenia Paseshnichenko ◽  
Aleksandr Yatsenko ◽  
Andrey Orekhov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chemical Composition ◽  
High Resolution ◽  
Electron Diffraction ◽  
Single Crystal ◽  
Room Temperature ◽  
Energy Dispersive ◽  
X Ray ◽  
Transmission Electron

AbstractA new method for synthesis of 2D nanocrystals in water was proposed. The use of perfluorothiophenolate ions as surfactant allowed us to produce 2D single-crystal nanosheets of CaS at pH=9 and flat nanocrystals of PbS at pH=9 at room temperature. Mesocrystalline nanobelts of CdS and mesocrystals of PbS were obtained at pH=3–5 and pH=10–12, respectively. Morphology, structure and chemical composition of nanoparticles were characterized by high-resolution transmission electron microscopy, electron diffraction and energy dispersive X-ray spectroscopy. A mechanism of nanoparticles formation was discussed.

scholarly journals Структурная эволюция молекулярного сегнетоэлектрика хлорида диизопропиламмония (DIPAC)

2020 ◽  
Vol 62 (7) ◽  
pp. 1055
Author(s):  
Н.И. Ускова ◽  
Е.В. Чарная ◽  
Д.Ю. Подорожкин ◽  
C.B. Барышников ◽  
И.В. Егорова ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Thermal Treatment ◽  
Room Temperature ◽  
Orthorhombic Structure ◽  
X Ray ◽  
Nuclear Magnetic

Changes in structure of a new molecular ferroelectric diisopropylammonium chloride (C6H16ClN, DIPAC) at room temperature were studied by high-resolution (CP-MAS) nuclear magnetic resonance (NMR) and X-ray analysis. NMR measurements were carried out for ^{13}С nuclei. Monoclinic ferroelectric and orthorhombic nonpolar phases as well as their coexistence were observed depending on time and thermal treatment. It was shown that the polar modification of DIPAC at room temperature transforms with time to the nonpolar orthorhombic structure. N. I. Uskova, E. V. Charnaya, L. Yu. Podorozhkin, S. V. Baryshnikov, I. V. Egorova, A. Yu. Milinskii

Tem Observation of Bubbles in He-Implanted α-Fe

1982 ◽  
Vol 40 ◽  
pp. 590-591
Author(s):  
D. M. Follstaedt ◽  
S. M. Myers
Keyword(s):  
Grain Boundary ◽  
Ion Implantation ◽  
Room Temperature ◽  
Hydrogen Isotopes ◽  
Void Swelling ◽  
Low Concentrations ◽  
Fundamental Understanding ◽  
Grain Boundary Embrittlement ◽  
Boundary Embrittlement

Helium has negligible solubility in metals, but in certain materials applications it is introduced athermally. This occurs, for example, through ion implantation from thermonuclear plasmas, tritium decay, and neutroninduced transmutation. Helium may have several detrimental effects, including grain boundary embrittlement, initiation of void swelling, and trapping of hydrogen isotopes. Hence a fundamental understanding of the behavior of He in metals is important. Implantation of He into a metal at room temperature usually leads to one of two microstructural configurations. At sufficiently low concentrations. He trapping by irradiation defects dominates.

STEM investigation of the chemistry and bonding changes associated with the grain boundary embrittlement of Cu by Bi

1996 ◽  
Vol 54 ◽  
pp. 526-527
Author(s):  
V. J. Keast ◽  
J. Bruley ◽  
D. B. Williams
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
High Current Density ◽  
High Current ◽  
Fracture Path ◽  
Scanning Electron Micrograph ◽  
Edge Structure ◽  
X Ray ◽  
Grain Boundary Embrittlement ◽  
Electron Energy Loss

It has long been known that trace amounts of Bi can embrittle Cu after appropriate heat treatments. The Bi segregates to the grain boundaries and weakens them such that failure occurs through intergranular fracture without plastic deformation. This behavior is demonstrated in the scanning electron micrograph of a typical Cu-Bi fracture surface in Figure 1. It is known that the Bi extends for only a few atomic layers into the grains on either side of the grain boundary. This narrow segregation width was been confirmed using Energy Dispersive X-ray Spectroscopy (EDS) on a VG HB603 STEM. Figure 2 shows the ratio of Bi to Cu as the probe is stepped across the grain boundary.The segregation behavior is well understood, however it is not yet properly understood how the Bi causes embrittlement once it is at the grain boundaries. The Bi must change the bonding at the boundaries so that the boundaries become weak and hence the most likely fracture path. The Electron Energy Loss Near Edge Structure (ELNES) coupled with the small probes and high current density available in a field emission STEM can provide information about the localized electronic structure and hence bonding at grain boundaries. Previous investigations indicated that the near edge structure of Cu was altered at the grain boundaries due to the presence of Bi.

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