Change of dislocation density in aluminium and lithium fluoride after annealing near the melting point under hydrostatic pressure

1968 ◽  
Vol 3 (1) ◽  
pp. 80-88 ◽  
Author(s):  
B. Ya. Pines ◽  
A. F. Syrenko
Keyword(s):  
Melting Point ◽  
Hydrostatic Pressure ◽  
Dislocation Density ◽  
Lithium Fluoride

scholarly journals Temperature Measurements in Athabasca Glacier, Alberta, Canada

1971 ◽  
Vol 10 (60) ◽  
pp. 339-349 ◽  
Author(s):  
W. S. B. Paterson
Keyword(s):  
Melting Point ◽  
Hydrostatic Pressure ◽  
Water Content ◽  
Melting Temperature ◽  
Small Difference ◽  
Temperature Measurements ◽  
Air Bubbles ◽  
Average Difference ◽  
Ablation Area ◽  
Pressure Melting

AbstractThe temperature in the ablation area of Athabasca Glacier is about —0.5°C at a depth of 10 m. Below 17 m the temperature is slightly below the calculated pressure melting point (average difference 0.01 deg) in some places. Heat produced by ice deformation is calculated as a function of depth in two bore holes. Only in about the lower half of the glacier thickness is this heat sufficient to maintain the ice at the observed temperature as the hydrostatic pressure is reduced by ablation. Freezing of water within the ice must provide heat for this purpose elsewhere in the glacier; it must also provide heat to maintain the deeper ice close to the melting point even though the 10 m temperature is negative. The minimum water content needed is estimated to be between 0.5 and 1%. It is argued that most of this water must be water trapped between grains when the ice formed from firn. The small difference from the pressure melting temperature measured below 17 m probably arises either from impurities or because, as a result of heat supplied for pressure-melting of ice around air bubbles, the ice is at the melting point corresponding to the bubble pressure rather than to the hydrostatic pressure.

Effect of Grain Size on Defects Density and Internal Stresses in Sub-Microcrystals

2009 ◽  
Vol 633-634 ◽  
pp. 605-611 ◽  
Author(s):  
Nina Koneva ◽  
Eduard Kozlov ◽  
N.A. Popova ◽  
M.V. Fedorischeva
Keyword(s):  
Grain Size ◽  
Hydrostatic Pressure ◽  
Dislocation Density ◽  
Crystal Lattice ◽  
Internal Stresses ◽  
Density Fraction ◽  
Tem Method ◽  
Scalar Dislocation Density

The paper is devoted to research of an influence of average grains size on scalar dislocation density, fraction of geometrically necessary dislocations, internal stresses and bending- torsion of crystal lattice. Polycrystals of submicrocrystalline copper produced by torsion under hydrostatic pressure were investigated by TEM method.

The Determination of Thermal Diffusivities of Thermal Energy Storage Materials: Part II—Molten Salts Beyond the Melting Point

1969 ◽  
Vol 91 (3) ◽  
pp. 189-197 ◽  
Author(s):  
K. Sreenivasan ◽  
M. Altman
Keyword(s):  
Thermal Diffusivity ◽  
Melting Point ◽  
Sodium Nitrate ◽  
Lithium Fluoride ◽  
Molten Salts ◽  
Liquid Lithium ◽  
Energy Storage Materials ◽  
Flux Measurements ◽  
The Difference ◽  
Thermal Diffusivities

A quasisteady method for measuring the thermal diffusivity of molten salts at temperatures above their melting point is described. Essentially, the difference between the temperature at the surface and at the center of a cylindrical container is measured for a constant rate of surface temperature rise. The liquid, whose thermal diffusivity is to be measured, is contained in a narrow annular groove concentric with the surface. The advantages of this method are: (a) no heat flux measurements are needed; (b) no liquid temperature need be measured; (c) theoretically assumed boundary conditions can be experimentally realized; (d) absence of convection can be experimentally verified. Results of measurements are reported for liquid lithium fluoride and sodium nitrate. The results for sodium nitrate agree with previously published results. The thermal conductivity of lithium fluoride can be empirically expressed in terms of the melting point, the molecular weight and the density, as k=0.9Tm1/2ρm2/3M−7/6

scholarly journals Thermodynamic and Kinetic Characteristics of Variations in Shapes of Ridges Formed on {100} Lithium Fluoride Surfaces

1991 ◽  
Vol 238 ◽  
Author(s):  
J. W. Bullard ◽  
A. M. Glaeser ◽  
Alan W. Searcy
Keyword(s):  
Theoretical Model ◽  
Melting Point ◽  
Single Crystals ◽  
Surface Diffusion ◽  
Lithium Fluoride ◽  
Kinetic Characteristics ◽  
Surface Sites ◽  
Diffusion Controlled ◽  
Shape Changes

ABSTRACTChannels with widths in the range from 5 μm to 25 μm were formed in {100} surfaces of LiF single crystals by a photolithographic technique. Specimens annealed at or above 0.90 Tm, where Tm is the melting point, and then quenched showed die channels and the ridges between them develop rounded profiles. Evolution of these profiles was evaluated for the various channel widths and for interchannel ridge spacings of 5 to 100 μm in terms of: a) an accepted theoretical model for a surface diffusion controlled process, and b) a model which assumes that shape changes depend only on the relative energies of attachment of atoms in surface sites with various surface curvatures. Either model is consistent with the experimental observations to within the reproducibility in measurements.

scholarly journals Temperature Measurements in Athabasca Glacier, Alberta, Canada

1971 ◽  
Vol 10 (60) ◽  
pp. 339-349 ◽  
Author(s):  
W. S. B. Paterson
Keyword(s):  
Melting Point ◽  
Hydrostatic Pressure ◽  
Water Content ◽  
Melting Temperature ◽  
Small Difference ◽  
Temperature Measurements ◽  
Air Bubbles ◽  
Average Difference ◽  
Ablation Area ◽  
Pressure Melting

AbstractThe temperature in the ablation area of Athabasca Glacier is about —0.5°C at a depth of 10 m. Below 17 m the temperature is slightly below the calculated pressure melting point (average difference 0.01 deg) in some places. Heat produced by ice deformation is calculated as a function of depth in two bore holes. Only in about the lower half of the glacier thickness is this heat sufficient to maintain the ice at the observed temperature as the hydrostatic pressure is reduced by ablation. Freezing of water within the ice must provide heat for this purpose elsewhere in the glacier; it must also provide heat to maintain the deeper ice close to the melting point even though the 10 m temperature is negative. The minimum water content needed is estimated to be between 0.5 and 1%. It is argued that most of this water must be water trapped between grains when the ice formed from firn. The small difference from the pressure melting temperature measured below 17 m probably arises either from impurities or because, as a result of heat supplied for pressure-melting of ice around air bubbles, the ice is at the melting point corresponding to the bubble pressure rather than to the hydrostatic pressure.

Voids in Irradiated Tungsten and Molybdenum

1969 ◽  
Vol 27 ◽  
pp. 190-191
Author(s):  
Robert C. Rau ◽  
Robert L. Ladd
Keyword(s):  
Melting Point ◽  
Fast Neutron ◽  
Neutron Irradiation ◽  
Elevated Temperatures ◽  
Irradiation Temperature ◽  
The Body ◽  
Face Centered Cubic ◽  
Body Centered Cubic ◽  
Cubic Metals ◽  
Face Centered

Recent studies have shown the presence of voids in several face-centered cubic metals after neutron irradiation at elevated temperatures. These voids were found when the irradiation temperature was above 0.3 Tm where Tm is the absolute melting point, and were ascribed to the agglomeration of lattice vacancies resulting from fast neutron generated displacement cascades. The present paper reports the existence of similar voids in the body-centered cubic metals tungsten and molybdenum.

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