Atomistic Image of the Kinetics of ‘Order-Order’ Reactions in Ni3Al+B

1995 ◽  
Vol 398 ◽  
Author(s):  
R. Kozubski ◽  
W. Pfeiler
Keyword(s):  
Activation Energy ◽  
Experimental Results ◽  
Vacancy Formation ◽  
Atomistic Model ◽  
High Activation ◽  
High Activation Energy ◽  
Parallel Processes ◽  
Kinetics Of

ABSTRACTIsothermal ‘order-order’ relaxations in Ll2-ordered N76Al24+0.19at.%B were studied by means of residual resistometry. This method made it possible to register very fine changes in the degree of LRO occurring about 1000K below the disordering temperature. The experimental results of two simultaneous processes being involved in these order-order relaxations with a high activation energy of 4.6eV are explained with an atomistic model of atomic jumps to nn vacancies. The parallel processes are connected with selected jumps of atoms to nn vacancies on different sublattices with a high activation energy of vacancy formation being involved.

Front instability in a condensed phase combustion model

2015 ◽  
Vol 4 (3) ◽  
pp. 153-176 ◽  
Author(s):  
Alexis Bonnet ◽  
Fathi Dkhil ◽  
Elisabeth Logak
Keyword(s):  
Activation Energy ◽  
Condensed Phase ◽  
Linear Instability ◽  
Combustion Model ◽  
Energy Limit ◽  
High Activation ◽  
Front Solution ◽  
High Activation Energy ◽  
Linearized Problem ◽  
Existence Of Zeros

AbstractWe consider a condensed phase (or solid) combustion model and its linearization around the travelling front solution. We construct an Evans function to characterize the eigenvalues of the linearized problem. We estimate this functional in the high activation energy limit. We deduce the existence of zeros with nonnegative real part for high activation energy, which proves the linear instability of the travelling front solution.

scholarly journals Gas-phase detonation propagation in mixture composition gradients

2012 ◽  
Vol 370 (1960) ◽  
pp. 567-596 ◽  
Author(s):  
D. A. Kessler ◽  
V. N. Gamezo ◽  
E. S. Oran
Keyword(s):  
Activation Energy ◽  
Reaction Model ◽  
Single Step ◽  
Mixture Composition ◽  
Composition Gradient ◽  
Detonation Properties ◽  
High Activation ◽  
Zone Structure ◽  
Detonation Cell ◽  
High Activation Energy

The propagation of detonations through several fuel–air mixtures with spatially varying fuel concentrations is examined numerically. The detonations propagate through two-dimensional channels, inside of which the gradient of mixture composition is oriented normal to the direction of propagation. The simulations are performed using a two-component, single-step reaction model calibrated so that one-dimensional detonation properties of model low- and high-activation-energy mixtures are similar to those observed in a typical hydrocarbon–air mixture. In the low-activation-energy mixture, the reaction zone structure is complex, consisting of curved fuel-lean and fuel-rich detonations near the line of stoichiometry that transition to decoupled shocks and turbulent deflagrations near the channel walls where the mixture is extremely fuel-lean or fuel-rich. Reactants that are not consumed by the leading detonation combine downstream and burn in a diffusion flame. Detonation cells produced by the unstable reaction front vary in size across the channel, growing larger away from the line of stoichiometry. As the size of the channel decreases relative to the size of a detonation cell, the effect of the mixture composition gradient is lessened and cells of similar sizes form. In the high-activation-energy mixture, detonations propagate more slowly as the magnitude of the mixture composition gradient is increased and can be quenched in a large enough gradient.

Anomalous high activation energy for creep in nanostructured 3YTZP/Ni cermets

2007 ◽  
Vol 27 (11) ◽  
pp. 3295-3299 ◽  
Author(s):  
A. Morales-Rodríguez ◽  
D. Gómez-García ◽  
T. Rodriguez-Suarez ◽  
S. Lopez-Esteban ◽  
C. Pecharroman ◽  
...  
Keyword(s):  
Activation Energy ◽  
High Activation ◽  
High Activation Energy

Cu-based metal-organic frameworks for highly sensitive X‑ray detector

2021 ◽  
Author(s):  
Zheng Li ◽  
Shuquan Chang ◽  
Haiqian Zhang ◽  
Yong Hu ◽  
Yulong Huang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Metal Organic Frameworks ◽  
High Activation ◽  
X Ray ◽  
High Activation Energy ◽  
Highly Sensitive ◽  
Metal Organic

Here, we constructed Pb-free Cu-DABDT-MOFs-based (DABDT = 2,5-diamino-1,4-benzenedithiol dihydrochloride) X-ray detectors. Combined with the advantage of high activation energy, Cu-DABDT-MOFs-based detector can effectively generate and capture electron under X-ray exposure...

The Mechanism of Superplastic Deformation with High Activation Energy

1991 ◽  
Vol 66-69 ◽  
pp. 1421-1424
Author(s):  
András Juhász ◽  
P. Tasnádi ◽  
Nguyen Q. Chinh ◽  
I. Kovács
Keyword(s):  
Activation Energy ◽  
Superplastic Deformation ◽  
High Activation ◽  
High Activation Energy

Non-uniqueness for flame propagation when the Lewis number is less than 1

1995 ◽  
Vol 6 (4) ◽  
pp. 287-306 ◽  
Author(s):  
Alexis Bonnet
Keyword(s):  
Activation Energy ◽  
Flame Propagation ◽  
Chemical Reaction ◽  
Sufficient Conditions ◽  
Lewis Number ◽  
Heat Diffusion ◽  
High Activation ◽  
High Activation Energy ◽  
One Step ◽  
Species Diffusion

We discuss the question of uniqueness of planar flames for a simple one-step chemical reaction. We show that when the Lewis number is less than unity (i.e. species diffusion is larger than heat diffusion) uniqueness cannot be generally assumed. An example with three flames, two of them being stable, is exhibited. Other related questions, such as sufficient conditions for uniqueness to hold and high activation energy limits, are discussed.

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