scholarly journals DETERMINACIÓN DEL COEFICIENTE DE AUTO-DIFUSIÓN SUPERFICIAL DEL HIELO IH

Anales AFA ◽  
2019 ◽  
pp. 6-9
Author(s):  
D. Stoler ◽  
M. Lado ◽  
R. Perdomo Arcila ◽  
G. Aguirre Varela ◽  
C.L. Di Prinzio
Keyword(s):  
Free Surface ◽  
Grain Boundary ◽  
Misorientation Angle ◽  
Silicone Oil ◽  
Optical Microscope ◽  
Self Diffusion

En este trabajo se estudió la evolución del ancho del surco formado por la intersección del borde de grano (BG) en una muestra de hielo bicristalina con la superficie libre de la misma. La muestra de hielo estudiada tenía una desorientación cristalina desconocida y fue sumergida en aceite de siliconas ultra puro a -5oC a fin de evitar procesos de evaporación. Se tomaron fotografías del surco cada 17 minutos durante 100 horas con un microscopio óptico y con estas imágenes se determinó la evolución del ancho del surco. Mediante ese estudio se pudo medir el coeficiente de autodifusión superficial del hielo a -5oC. In this work the evolution of the groove in a bicrystalline ice sample was studied. The groove is formed by the intersection of the grain boundary(BG) with the free surface. The ice sample studied had arbitrary misorientation angle and was immersed in ultra pure silicone oil at -5oC in order to avoid evaporation processes. Photographs of the groove was taken every 17 minutes for 100 hours with an optical microscope and the evolution of the groove was determined with these images. The coefficient of superficial self-diffusion of ice at -5oC has been measured

scholarly journals Superficial self-diffusion coefficient in Ih-ICE

2020 ◽  
Vol 10 (2) ◽  
pp. 153-160
Author(s):  
Carlos Leonardo Di Prinzio ◽  
Damian Stoler ◽  
Guillermo Aguirre Varela ◽  
Esteban Druetta
Keyword(s):  
Diffusion Coefficient ◽  
Free Surface ◽  
Grain Boundary ◽  
Silicone Oil ◽  
Optical Microscope ◽  
Boundary Groove ◽  
Self Diffusion ◽  
Self Diffusion Coefficient

The evolution of the grain boundary groove in a bicrystalline ice sample was studied in this work. The groove is formed by the intersection of the grain boundary with the free surface. The bicrystalline ice sample had an arbitrary misorientation and was immersed in ultra-pure silicone oil at -5°C in order to avoid evaporation processes. Photographs of the groove were taken every 17 minutes for 100 hours with an optical microscope and the evolution of the groove was determined from these images. Through this study, it was possible to measure the coefficient of surface self-diffusion of the ice at -5°C.

scholarly journals Effect of light elements impurity atoms on grain boundary diffusion in FCC metals: a molecular dynamics simulation

2020 ◽  
Vol 62 (12) ◽  
pp. 930-935
Author(s):  
G. M. Poletaev ◽  
I. V. Zorya ◽  
R. Yu. Rakitin ◽  
M. D. Starostenkov
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Crystal Lattice ◽  
Grain Boundaries ◽  
Free Volume ◽  
Misorientation Angle ◽  
Light Elements ◽  
Self Diffusion ◽  
Impurity Atoms ◽  
Metal Atoms

Effect of carbon and oxygen impurity atoms on diffusion along the tilt grain boundaries with <100> and <111> misorientation axis in metals with FCC lattice was studied by mean of molecular dynamics method. Ni, Ag, and Al were considered as metals. Interactions of metal atoms with each other were described by many-particle Clery-Rosato potentials constructed within the framework of tight binding model. To describe interactions of atoms of light elements impurities with metal atoms and atoms of impurities with each other, Morse pair potentials were used. According to obtained results, impurities in most cases lead to an increase in self-diffusion coefficient along the grain boundaries, which is caused by deformation of crystal lattice near the impurity atoms. Therefore, additional distortions and free volume are formed along the boundaries. It is more expressed for carbon impurities. Moreover, with an increase in concentration of carbon in the metal, an increase in coefficient of grain-boundary self-diffusion was observed first, and then a decrease followed. This behavior is explained by formation of aggregates of carbon atoms at grain boundary, which leads to partial blocking of the boundary. Oxygen atoms had smaller effect on diffusion along the grain boundaries, which is apparently explained by absence of a tendency to form aggregates and lesser deformation of crystal lattice around impurity. The greatest effect of impurities on self-diffusion along the grain boundaries among the examined metals was observed for nickel. Nickel has the smallest lattice parameter, impurity atoms deform its lattice around itself more than aluminum and silver, and therefore they create relatively more lattice distortions in it and additional free volume along the grain boundaries, which lead to an increase in diffusion permeability. Diffusion coefficients along the high-angle boundaries with misorientation angle of 30° turned out to be approximately two times higher than along low-angle boundaries with a misorientation angle of 7°. Diffusion along the <100> grain boundaries flowed more intensively than along the <111> boundaries.

scholarly journals FLATTENING OF A SCRATCH ON ICE PURE SURFACE

Anales AFA ◽  
2019 ◽  
Vol Vol.30 (Vol.30 N.2) ◽  
pp. 31-35
Author(s):  
D. Stoler ◽  
M. Lado ◽  
G Aguirre Varela ◽  
C. L. Di Prinzio
Keyword(s):  
Diffusion Coefficient ◽  
Surface Diffusion ◽  
Line Width ◽  
Silicone Oil ◽  
Optical Microscope ◽  
Self Diffusion ◽  
Metallic Sheet ◽  
Self Diffusion Coefficient ◽  
Pure Surface ◽  
Effect Of Surface

In this work the evolution of the width of a line (groove) traced on the surface of a sample of bi-crystalline ice, by means of a metallic sheet, in a direction almost orthogonal to the grain edge (BG) was studied. To perform the measurements, the sample of ice submerged in ultrapure silicone oil was maintained at -5 ºC to prevent evaporation from occurring and isolate the effect of surface diffusion in this way. Photographs of the groove were periodically taken, approximately for 100 hours, using a camera coupled to an optical microscope. From these images the evolution of the line width was studied. Finally, the ice self-diffusion coefficient was determined at -5 ºC.

On the role of tin underlays for the prevention of thermal grooving in thin gold films

1986 ◽  
Vol 44 ◽  
pp. 732-733
Author(s):  
Jin Young Kim ◽  
R. E. Hummel ◽  
R. T. DeHoff
Keyword(s):  
Thin Film ◽  
Free Surface ◽  
Grain Boundary ◽  
Beneficial Effect ◽  
Failure Mechanism ◽  
Failure Mechanisms ◽  
Distinct Advantage ◽  
Gold Films ◽  
Gold Thin Film

Gold thin film metallizations in microelectronic circuits have a distinct advantage over those consisting of aluminum because they are less susceptible to electromigration. When electromigration is no longer the principal failure mechanism, other failure mechanisms caused by d.c. stressing might become important. In gold thin-film metallizations, grain boundary grooving is the principal failure mechanism.Previous studies have shown that grain boundary grooving in gold films can be prevented by an indium underlay between the substrate and gold. The beneficial effect of the In/Au composite film is mainly due to roughening of the surface of the gold films, redistribution of indium on the gold films and formation of In2O3 on the free surface and along the grain boundaries of the gold films during air annealing.

STUDY OF THE GRAIN BOUNDARY MIGRATION IN A TRICRISTAL PURE ICE WITH BUBBLES

Anales AFA ◽  
2019 ◽  
Vol 30 (3) ◽  
pp. 47-51
Author(s):  
P.I. Achával ◽  
C. L. Di Prinzio
Keyword(s):  
Monte Carlo ◽  
Grain Boundary ◽  
Numerical Simulations ◽  
Triple Junction ◽  
Boundary Migration ◽  
Optical Microscope ◽  
Physical Parameters ◽  
Grain Boundary Migration

In this paper the migration of a grain triple junction in apure ice sample with bubbles at -5°C was studied for almost 3hs. This allowed tracking the progress of the Grain Boundary (BG) and its interaction with the bubbles. The evolution of the grain triple junction was recorded from successive photographs obtained witha LEICA® optical microscope. Simultaneously, numerical simulations were carried out using Monte Carlo to obtain some physical parameters characteristic of the BG migration on ice.

An Experimental Study of Cavity Nucleation During Superplastic Deformation

1990 ◽  
Vol 196 ◽  
Author(s):  
Jiang Xinggang ◽  
Cui Jianzhong ◽  
Ma Longxiang
Keyword(s):  
Grain Boundary ◽  
Superplastic Deformation ◽  
Thermomechanical Processing ◽  
High Stress ◽  
High Strength ◽  
Optical Microscope ◽  
Grain Boundary Sliding ◽  
Cavity Nucleation ◽  
High Stress Concentration ◽  
Voltage Electron

ABSTRACTCavity nucleation during superplastic deformation of a high strength aluminium alloy has been studied using a high voltage electron microscope and an optical microscope. The results show that cavities nucleation is due only to superplastic deformation and not to pre-existing microvoids which may be introduced during thermomechanical processing. The main reason for cavity nucleation is the high stress concentration at discontinuties in the plane of the grain boundary due to grain boundary sliding.

Microstructural Fractal Dimension of AISI 316L Steel

1994 ◽  
Vol 367 ◽  
Author(s):  
M. Hinojosa ◽  
R. Rodréguez ◽  
U. Ortiz
Keyword(s):  
Fractal Dimension ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Tensile Strain ◽  
Optical Microscope ◽  
Standard Test ◽  
Test Method ◽  
Aisi 316L ◽  
316L Steel ◽  
Deformation Processes

AbstractFractal dimension of the microstructure of AISI 316L steel (17 Cr, 12.7 Ni, 2.1 Mo, 1. 5 Mn, 0.01 C) with different degrees of strain were obtained from Richardson plots of grain boundary perimeter against magnification. Grain boundaries were revealed using conventional metallographic techniques and measurements were taken with the aid of an automatic image analizer (Quantimet 520) attached to an optical microscope. The magnifications used were 50, 100, 200, 400, and 1000X. The samples were obtained from a 4” diameter tubing, machined according to ASTM A370 standard test method and deformed to 5, 10, 15, and 20 % tensile strain. The results show that the fractal dimension of the grain boundaries changes as deformation is imparted to the material.These results suggest that fractal dimension may be used to describe microstructural evolution of metals during deformation processes.

Grain Boundary Self-Diffusion in Silver Bicrystals

1991 ◽  
Vol 66-69 ◽  
pp. 843-848 ◽  
Author(s):  
J. Sommer ◽  
Christian Herzig ◽  
S. Mayer ◽  
W. Gust
Keyword(s):  
Grain Boundary ◽  
Self Diffusion

Epitaxial Aluminum Electrodes on Theta Rotated Y-X LiTaO3 Piezoelectric Substrate for High Power Durable SAW Duplexers.

2004 ◽  
Vol 833 ◽  
Author(s):  
Osamu Nakagawara ◽  
Hironori Suzuki ◽  
Shuji Yamato ◽  
Masayuki Hasegawa ◽  
Hideharu Ieki
Keyword(s):  
Grain Boundary ◽  
High Power ◽  
Intermediate Layer ◽  
Deposition Temperature ◽  
Film Material ◽  
Epitaxial Relationship ◽  
Self Diffusion ◽  
Process Sequence ◽  
Aluminum Electrodes ◽  
Piezoelectric Substrate

ABSTRACTHigh power durable electrodes have been successfully grown on 38.5° rotated Y-X LiTaO3 piezoelectric substrates featuring epitaxial Al films with a pseudo-homoepitaxial Ti intermediate layer. We found that a two-step process sequence in the deposition temperature of an intermediate layer could make it possible for an Al/Ti structure to grow epitaxially on low-cut-angle Y-X LiTaO3. Specified epitaxial relationship was Al(111)<011>//Ti(001)<100>//LiTaO3(001)<100>. Duplexers with epitaxial Al electrodes had a breakdown power above 6 W and more than ten times longer lifetime in contrast to filters with polycrystalline electrodes of which the breakdown power is 3.4 W. Epitaxial electrodes with extremely less grain boundary can improve power durability because self-diffusion of Al atoms occurs mainly in the grain boundary of the film. Material variation of epitaxial electrodes will be discussed as well.

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