Platinum Group Metals Base Refractory Superalloys

1996 ◽  
Vol 460 ◽  
Author(s):  
Y. Yamabe-Mitarai ◽  
Y. Koizumi ◽  
H. Murakami ◽  
Y. Ro ◽  
T. Maruko ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Platinum Group Metals ◽  
Compression Tests ◽  
Two Phase ◽  
X Ray ◽  
Melting Temperatures ◽  
High Temperature Materials ◽  
Transmission Electron ◽  
Two Phases

ABSTRACTIr- and Rh-base refractory superalloys with an fee and Lb two phase structure similar to Ni-base superalloys, yet with considerably higher melting temperatures have been proposed. Fee and Ll2 two phases were observed in these alloys by transmission electron microscopy and X-ray powder diffractometry. The compression tests of these alloys showed that the strengths of several alloys were about 200 MPa at 1800 °C and these alloys have potential to become ultra-high temperature materials for use in power engineering field.

scholarly journals Revisiting the Bøggild Intergrowth in Iridescent Labradorite Feldspars: Ordering, Kinetics, and Phase Equilibria

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 727
Author(s):  
Shiyun Jin ◽  
Huifang Xu ◽  
Seungyeol Lee
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atom Probe ◽  
Phase Region ◽  
Two Phase ◽  
Subsolidus Phase ◽  
Plagioclase Feldspar ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission

The enigmatic Bøggild intergrowth in iridescent labradorite crystals was revisited in light of recent work on the incommensurately modulated structures in the intermediated plagioclase. Five igneous samples and one metamorphic labradorite sample with various compositions and lamellar thicknesses were studied in this paper. The lamellar textures were characterized with conventional transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). The compositions of individual lamellae were analyzed with high-resolution energy-dispersive X-ray spectroscopy (EDS) mapping and atom probe tomography (APT). The average structure states of the studied samples were also compared with single-crystal X-ray diffraction data (SC-XRD). The Na-rich lamellae have a composition of An44–48, and the Ca-rich lamellae range from An56 to An63. Significant differences between the lamellar compositions of different samples were observed. The compositions of the Bøggild intergrowth do not only depend on the bulk compositions, but also on the thermal history of the host rock. The implications on the subsolidus phase relationships of the plagioclase feldspar solid solution are discussed. The results cannot be explained by a regular symmetrical solvus such as the Bøggild gap, but they support an inclined two-phase region that closes at low temperature.

Nanostructure evolution and properties of two-phase nc-Ti(C, N)/a-(C, CNx) nanocomposites by high-resolution transmission electron microscopy, x-ray photoelectron spectroscopy, and Raman spectroscopy

2007 ◽  
Vol 22 (9) ◽  
pp. 2460-2469 ◽  
Author(s):  
Y.H. Lu ◽  
Y.G. Shen
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Solid Solution ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Photoelectron Spectroscopy ◽  
Atomic Ratio ◽  
Two Phase ◽  
X Ray ◽  
Transmission Electron

High-resolution transmission electron microscopy, x-ray photoelectron spectroscopy (XPS), and Raman spectroscopy were used to study phase configuration and nanostructure evolutions of Ti–Cx–Ny thin films with different amounts of C incorporation. It was found that the atomic ratio of (C + N)/Ti played a crucial role in phase configuration and nanostructure evolutions as well as mechanical behaviors. When the ratio was less than one unit, a nanocrystalline (nc-) Ti(C, N) solid solution was formed by way of dissolution of C into TiN lattice. When this dissolution reached saturation, precipitation of a small amount of amorphous (a-) C phase along nc-Ti(C, N) grains was followed with more C incorporation. Further increase of C content (up to ∼19 at.% C) made the amorphous phase fully wet nanocrystallites, which resulted in the formation of two-phase nanocomposite thin films with microstructures comprising of ∼5 nm nc-Ti(C,N) crystallites separated by ∼0.5 nm a-(C, CNx) phase. Thicker amorphous walls and smaller sized grains were followed when the C content was further increased, accompanying with the formation of some disorders and defects in nc-grains and amorphous matrices. When the C content was increased to ∼48 at.%, 1–3 nm nanocrystallites with an average size of ∼2 nm were embedded into amorphous matrices. Both microhardness and residual compressive stress values were increased with increase of the atomic ratio in solid solution thin films when the atomic ratio value was less than one unit. Their maximums were obtained at stiochiometry nc-Ti(C,N) solid solution. Enhancement of hardness values was attributed to solid solution effect.

Development of Platinum-Group-Metal Superalloys for High-Temperature Use

MRS Bulletin ◽  
2003 ◽  
Vol 28 (9) ◽  
pp. 632-638 ◽  
Author(s):  
L. A. Cornish ◽  
B. Fischer ◽  
R. Völkl
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Oxide Dispersion Strengthened ◽  
Platinum Group Metal ◽  
Platinum Group Metals ◽  
Compression Tests ◽  
Two Phase ◽  
Transmission Electron ◽  
Oxide Particles ◽  
Platinum Group

AbstractSuperalloys based on platinum-group metals are being developed for high-temperature applications. These alloys have two-phase structures comprising either ordered precipitates in a matrix analogous to the nickel-based superalloys or a fine dispersion of oxide particles in a matrix analogous to oxide-dispersion-strengthened nickel-based alloys. Currently, alloys based on iridium, rhodium, and platinum have been obtained. This article reviews the rationale of developments and the progress made in this area. Oxidation and compression tests as well as characterization with scanning electron microscopy and transmission electron microscopy were undertaken. These tests showed encouraging results, and further work is being done on new alloying additions and tensile testing.

On Microstrucitural Evolution in Gas Atomized Ti-50 at.% Al-2 at.% Nb Powder

1988 ◽  
Vol 133 ◽  
Author(s):  
Donald S. Shih ◽  
Gary K. Scarr ◽  
James C. Chesnutt
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Powder ◽  
Microstructural Development ◽  
X Ray ◽  
Transmission Electron ◽  
Helium Gas ◽  
Two Phases ◽  
20 Nm

ABSTRACTMicrostructural development in helium gas atomized Ti-50A1-2Nb (at.%) powder has been characterized using x-ray diffractometry and transmission electron microscopy. The structure of the as-atomized powder was a mixture of two phases: an ordered fct (L10)γ TiAl phase and an hcp α Ti phase containing fine (≈ 10–20 nm) D019 α2 domains. Large powder (≈ 250 μm) contained ≈ 14 volume % hcp phase, while fine powder (≈37 μm) contained ≈ 72 volume % hcp phase. However, this α+α2 constituent was metastable and transformed to the γ phase during annealing.

Phase Transformations in Ti-7w/oMo-3w/oMe Alloy

1974 ◽  
Vol 32 ◽  
pp. 514-515
Author(s):  
S. Fujishiro
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Mechanical Processing ◽  
Ray Method ◽  
X Ray ◽  
Transmission Electron ◽  
Water Quench ◽  
Alpha Beta

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.

A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

1982 ◽  
Vol 40 ◽  
pp. 722-723 ◽  
Author(s):  
R. Gronsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Computer Simulations ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

Dislocations in alumina deformed by prismatic slip

1978 ◽  
Vol 36 (1) ◽  
pp. 606-607
Author(s):  
J. Cadoz ◽  
J. Castaing ◽  
J. Philibert
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Basal Slip ◽  
Prismatic Slip ◽  
Compression Tests ◽  
Thin Sections ◽  
Burgers Vector ◽  
Maximum Deformation ◽  
Transmission Electron ◽  
Mechanical Thinning

Plastic deformation of alumina has been much studied; basal slip occurs and dislocation structures have been investigated by transmission electron microscopy (T.E.M.) (1). Non basal slip has been observed (2); the prismatic glide system <1010> {1210} has been obtained by compression tests between 1400°C and 1800°C (3). Dislocations with <0110> burgers vector were identified using a 100 kV microscope(4).We describe the dislocation structures after prismatic slip, using high voltage T.E.M. which gives much information.Compression tests were performed at constant strainrate (∿10-4s-1); the maximum deformation reached was 0.03. Thin sections were cut from specimens deformed at 1450°C, either parallel to the glide plane or perpendicular to the glide direction. After mechanical thinning, foils were produced by ion bombardment. Details on experimental techniques can be obtained through reference (3).

Magnesium and sulfur in mast cell and basophil granules of lower vertebrates in relation with histamine

1992 ◽  
Vol 50 (2) ◽  
pp. 1596-1597
Author(s):  
Kenichi Takaya
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Mast Cell ◽  
Mast Cells ◽  
Tree Frog ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Fresh Frozen ◽  
Ultrathin Sections

Mast cell and basophil granules of the vertebrate contain heparin or related sulfated proteoglycans. Histamine is also present in mammalian mast cells and basophils. However, no histamine is detected in mast cell granules of the amphibian or fish, while it is shown in those of reptiles and birds A quantitative x-ray microanalysis of mast cell granules of fresh frozen dried ultrathin sections of the tongue of Wistar rats and tree frogs disclosed high concentrations of sulfur in rat mast cell granules and those of sulfur and magnesium in the tree frog granules. Their concentrations in tree frog mast cell granules were closely correlated (r=0.94).Fresh frozen dried ultrathin sections and fresh air-dried prints of the tree frog tongue and spleen and young red-eared turtle (ca. 6 g) spleen and heart blood were examined by a quantitative energy-dispersive x-ray microanalysis (X-650, Kevex-7000) for the element constituents of the granules of mast cells and basophils. The specimens were observed by transmission electron microscopy (TEM) (80-200 kV) and followed by scanning transmission electron microscopy (STEM) under an analytical electron microscope (X-650) at an acceleration voltage of 40 kV and a specimen current of 0.2 nA. A spot analysis was performed in a STEM mode for 100 s at a specimen current of 2 nA on the mast cell and basophil granules and other areas of the cells. Histamine was examined by the o-phthalaldehyde method.

scholarly journals Quartz Crystallite Size and Moganite Content as Indicators of the Mineralogical Maturity of the Carboniferous Chert: The Case of Cherts from Eastern Asturias (Spain)

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 611
Author(s):  
Celia Marcos ◽  
María de Uribe-Zorita ◽  
Pedro Álvarez-Lloret ◽  
Alaa Adawy ◽  
Patricia Fernández ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Crystallite Size ◽  
Archaeological Sites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Infrared And Raman Spectroscopy ◽  
First Time ◽  
Geological Formations

Chert samples from different coastal and inland outcrops in the Eastern Asturias (Spain) were mineralogically investigated for the first time for archaeological purposes. X-ray diffraction, X-ray fluorescence, transmission electron microscopy, infrared and Raman spectroscopy and total organic carbon techniques were used. The low content of moganite, since its detection by X-ray diffraction is practically imperceptible, and the crystallite size (over 1000 Å) of the quartz in these cherts would be indicative of its maturity and could potentially be used for dating chert-tools recovered from archaeological sites. Also, this information can constitute essential data to differentiate the cherts and compare them with those used in archaeological tools. However, neither composition nor crystallite size would allow distinguishing between coastal and inland chert outcrops belonging to the same geological formations.

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