Melting Point Measurements for Quasicrystalline Phases

1986 ◽  
Vol 74 ◽  
Author(s):  
J. A. Knapp ◽  
D. M. Follstaedt
Keyword(s):  
Melting Point ◽  
Congruent Melting ◽  
Surface Layers ◽  
Congruent Melting Point ◽  
Fine Grained ◽  
Decagonal Phase ◽  
Formation Kinetics ◽  
Beam Heating ◽  
Kinetics Of ◽  
Electron Beam Heating

AbstractMelting transitions of metastable quasicrystalline phases of Al-Mn have been observed using rapid electron-beam heating of fine-grained icosahedral surface layers. The congruent melting-point for icosahedral Al80 Mn20 was directly measured to be 910±20°C. Heating to higher temperatures shows another transition which is inferred to correspond to the liquidus of the decagonal phase at 965±20°C for 20 at.% Mn. The microstructure and formation kinetics of the decagonal phase are discussed, and its electron diffraction is described.

Aqueous nonelectrolyte solutions. Part XIX. Congruent dissociation melting point and the formula of structure II methane hydrate

2003 ◽  
Vol 81 (2) ◽  
pp. 179-185 ◽  
Author(s):  
David N Glew
Keyword(s):  
Melting Point ◽  
Standard Error ◽  
Pressure Measurement ◽  
Methane Hydrate ◽  
Equilibrium Constants ◽  
Congruent Melting ◽  
Stability Range ◽  
Congruent Melting Point ◽  
Quadruple Point ◽  
Dissociation Equilibrium

Twenty-four equilibrium pressures, P(h2l1g), of structure II methane hydrate h2 with water l1 between 27.0 and 46.9°C are well represented by a four-parameter equation, which indicates a standard error (SE) of 1.95% on a single pressure measurement. Forty equilibrium constants Kp(h2[Formula: see text]l1g) for dissociation of structure II methane hydrate into water and methane between 27.0 and 47.7°C and at pressures up to 784 MPa at 45.0°C are best represented by a three-parameter thermodynamic equation, which indicates an SE 1.25% on a single Kp(h2[Formula: see text]l1g) determination. The congruent dissociation melting point C(h2l1gxm) of structure II methane hydrate is at 47.71°C with SE 0.03°C and at pressure 533 MPa with SE 5 MPa. The congruent Kp(h2[Formula: see text]l1g) is 102.9 with SE 0.3 MPa, ΔH°t(h2[Formula: see text]l1g) is 61 531 with SE 244 J mol–1, and the congruent formula is CH4·5.670H2O with SE 0.061H2O. At congruent point ΔV(h2[Formula: see text]l1g) = 0 and its estimate is 1.0 with SE 1.6 cm3 mol–1. Stability range of structure II methane hydrate with water extends from quadruple point Q(h1h2l1g) at 26.7°C and 55.5 MPa up to quadruple point Q(h2h3l1g) at 47.3°C and 620 MPa. The metastability range of structure I methane hydrate with water is discussed.Key words: methane hydrate, clathrate structure II, stability range, dissociation equilibrium constant, formula, congruent melting point, metastability of structure I hydrate.

scholarly journals Determination of the CoTi congruent melting point and thermodynamic reassessment of the Co-Ti system

2001 ◽  
Vol 32 (9) ◽  
pp. 2175-2186 ◽  
Author(s):  
A. V. Davydov ◽  
U. R. Kattner ◽  
D. Josell ◽  
R. M. Waterstrat ◽  
W. J. Boettinger ◽  
...  
Keyword(s):  
Melting Point ◽  
Congruent Melting ◽  
Congruent Melting Point

Morphological transition in the cellular structure of single crystals of nickel-tungsten alloys near the congruent melting point

2005 ◽  
Vol 50 (S1) ◽  
pp. S130-S135
Author(s):  
V. M. Azhazha ◽  
A. N. Ladygin ◽  
V. Ja. Sverdlov ◽  
P. D. Zhemanyuk ◽  
V. V. Klochikhin
Keyword(s):  
Melting Point ◽  
Single Crystals ◽  
Cellular Structure ◽  
Morphological Transition ◽  
Congruent Melting ◽  
Congruent Melting Point ◽  
Tungsten Alloys ◽  
Nickel Tungsten

Fission Gas Bubbles in Fractured UO2

1968 ◽  
Vol 26 ◽  
pp. 286-287
Author(s):  
O. M. Katz
Keyword(s):  
Electron Microscopy ◽  
Thermal Gradient ◽  
Gas Bubbles ◽  
Inert Gas ◽  
Thermal Gradients ◽  
Fission Gas ◽  
Beam Heating ◽  
Limited Application ◽  
Bubble Characteristics ◽  
Electron Beam Heating

The swelling of irradiated UO2 has been attributed to the migration and agglomeration of fission gas bubbles in a thermal gradient. High temperatures and thermal gradients obtained by electron beam heating simulate reactor behavior and lead to the postulation of swelling mechanisms. Although electron microscopy studies have been reported on UO2, two experimental procedures have limited application of the results: irradiation was achieved either with a stream of inert gas ions without fission or at depletions less than 2 x 1020 fissions/cm3 (∼3/4 at % burnup). This study was not limited either of these conditions and reports on the bubble characteristics observed by transmission and fractographic electron microscopy in high density (96% theoretical) UO2 irradiated between 3.5 and 31.3 x 1020 fissions/cm3 at temperatures below l600°F. Preliminary results from replicas of the as-polished and etched surfaces of these samples were published.

Elaboration and Characterization of the Properties of Refractory Cr Base Alloys

2010 ◽  
Vol 72 ◽  
pp. 46-52 ◽  
Author(s):  
Laurent Royer ◽  
Stéphane Mathieu ◽  
Christophe Liebaut ◽  
Pierre Steinmetz
Keyword(s):  
Mechanical Properties ◽  
Melting Point ◽  
Molten Glass ◽  
Energy Production ◽  
Creep Properties ◽  
Refractory Alloys ◽  
Industrial Use ◽  
Kinetics Of ◽  
Selection Of

For energy production and also for the glass industry, finding new refractory alloys which could permit to increase the process temperatures to 1200°C or more is a permanent challenge. Chromium base alloys can be good candidates, considering the melting point of Cr itself, and also its low corrosion rate in molten glass. Two families of alloys have been studied for this purpose, Cr-Mo-W and Cr-Ta-X alloys (X= Mo, Si..). A finer selection of compositions has been done, to optimize their chemical and mechanical properties. Kinetics of HT oxidation by air, of corrosion by molten glass and also creep properties of several alloys have been measured up to 1250°C. The results obtained with the best alloys (Cr-Ta base) give positive indications as regards the possibility of their industrial use.

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