Cavity Formation and Dipolar Contribution to the Gauche−Trans Isomerization of 1-Chloropropane and 1,2-Dichloroethane

2001 ◽  
Vol 105 (2) ◽  
pp. 520-526 ◽  
Author(s):  
Yanira Meléndez-Pagán ◽  
Brian E. Taylor ◽  
Dor Ben-Amotz
Keyword(s):  
Cavity Formation ◽  
Trans Isomerization ◽  
Dipolar Contribution

A TEM study of the effect of oxygen on nanocavity formation and precipitation in rapid - solidified Fe-16Ni-9Cr stainless steels

1994 ◽  
Vol 52 ◽  
pp. 700-701
Author(s):  
S. Wisutmethangoon ◽  
T. F. Kelly ◽  
J.E. Flinn
Keyword(s):  
Stainless Steels ◽  
High Mobility ◽  
Hot Extrusion ◽  
Extrusion Ratio ◽  
Gas Atomization ◽  
Cavity Formation ◽  
Nucleation Sites ◽  
Heat Treated ◽  
Different Types ◽  
Effect Of Oxygen

Vacancies are introduced into the crystal phase during quenching of rapid solidified materials. Cavity formation occurs because of the coalescence of the vacancies into a cluster. However, because of the high mobility of vacancies at high temperature, most of them will diffuse back into the liquid phase, and some will be lost to defects such as dislocations. Oxygen is known to stabilize cavities by decreasing the surface energy through a chemisorption process. These stabilized cavities, furthermore, act as effective nucleation sites for precipitates to form during aging. Four different types of powders with different oxygen contents were prepared by gas atomization processing. The atomized powders were then consolidated by hot extrusion at 900 °C with an extrusion ratio 10,5:1. After consolidation, specimens were heat treated at 1000 °C for 1 hr followed by water quenching. Finally, the specimens were aged at 600 °C for about 800 hrs. TEM samples were prepared from the gripends of tensile specimens of both unaged and aged alloys.

“Cavity” formation in superplastically deformed aluminium alloys

1990 ◽  
Vol 48 (4) ◽  
pp. 958-959
Author(s):  
A. Cziráki ◽  
E. Ková-csetényi ◽  
T. Torma ◽  
T. Turmezey
Keyword(s):  
Grain Boundaries ◽  
Aluminium Alloys ◽  
Superplastic Deformation ◽  
Volume Fraction ◽  
Superplastic Forming ◽  
Polished Surface ◽  
Cavity Formation ◽  
Stress Concentrations ◽  
Electron Microscopic ◽  
Commercial Aluminium

It is known that the formation of cavities during superplastic deformation can be correlated with the development of stress concentrations at irregularities along grain boundaries such as particles, ledges and triple points. In commercial aluminium alloys Al-Fe-Si particles or other coarse constituents may play an important role in cavity formation.Cavity formation during superplastic deformation was studied by optical metallography and transmission scanning electron microscopic investigations on Al-Mg-Si and Al-Mg-Mn alloys. The structure of particles was characterized by selected area diffraction and X-ray micro analysis. The volume fraction of “voids” was determined on mechanically polished surface.It was found by electron microscopy that strongly deformed regions are formed during superplastic forming at grain boundaries and around coarse particles.According to electron diffraction measurements these areas consist of small micro crystallized regions. See Fig.l.Comparing the volume fraction and morphology of cavities found by optical microscopy a good correlation was established between that of micro crystalline regions.

Cis–trans isomerization and optical laser writing in new heterocycle based azo-polyurethanes

2012 ◽  
Vol 34 (4) ◽  
pp. 724-728 ◽  
Author(s):  
Antonio Ambrosio ◽  
Fabio Borbone ◽  
Antonio Carella ◽  
Roberto Centore ◽  
Sandra Fusco ◽  
...  
Keyword(s):  
Laser Writing ◽  
Trans Isomerization ◽  
Optical Laser

Solvent and viscosity effect on the kinetics of the thermal cis-trans isomerization of 3'-nitro-4-diethylaminoazobenzene

1989 ◽  
Vol 11 (3) ◽  
pp. 179-189 ◽  
Author(s):  
Bruno Marcandalli ◽  
Pier Luigi Beltrame ◽  
Ernestina Dubini-Paglia ◽  
Alberto Seves
Keyword(s):  
Viscosity Effect ◽  
Trans Isomerization ◽  
Kinetics Of

The Crystallization of Modified Cis-Polybutadiene

1960 ◽  
Vol 33 (3) ◽  
pp. 699-702
Author(s):  
G. S. Trick
Keyword(s):  
Melting Point ◽  
Crosslink Density ◽  
Fixed Temperature ◽  
Trans Isomerization

Abstract From a sample of polybutadiene of high cis-1,4 content, the microstructure is modified by cis-trans isomerization or by crosslinking. Measurements of rates of crystallization and melting point are made on the modified samples. An increase in irons content or crosslink density markedly decreases the rate of crystallization at a fixed temperature. It is found, however, that this retardation in rate may usually be accounted for by the depressed melting point of the modified samples.

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