Reaction Pathway Analysis of Homogeneous Dislocation Nucleation in a Perfect Molybdenum Crystal

2011 ◽  
Vol 1297 ◽  
Author(s):  
Hasan A. Saeed ◽  
Satoshi Izumi ◽  
Shotaro Hara ◽  
Shinsuke Sakai
Keyword(s):  
Applied Stress ◽  
Pathway Analysis ◽  
Sampling Method ◽  
Reaction Pathway ◽  
Perfect Crystal ◽  
Dislocation Nucleation ◽  
Stress Range ◽  
Elastic Band ◽  
Burgers Vector ◽  
Reaction Pathway Analysis

ABSTRACTReaction pathway analysis was carried out for homogeneous dislocation nucleation in perfect crystal Mo. The reaction sampling method employed was based on the Nudged Elastic Band algorithm and other extended schemes. Results obtained were compared with corresponding results for Cu and Si. The stress range for activation energies less than 5 eV is found to be considerably higher for Mo than those for Cu as well as Si. Stresses in excess of 12 GPa make homogeneous dislocation nucleation in Mo an unrealistic transition. The results also show the dislocation cores under this stress range to be diffused, with shear displacement of particles being considerably less than the Burgers vector. Depending on the applied stress, displacement of extra slip-plane atoms can be considerable in Mo. This is in contrast to Cu, in which dislocation nucleation is essentially a two-plane phenomenon.

Transition Pathway Analysis of Homogeneous Dislocation Nucleation in a Perfect Silicon Crystal

2009 ◽  
Vol 1224 ◽  
Author(s):  
Hasan Aftab Saeed ◽  
Satoshi Izumi ◽  
Shotaro Hara ◽  
Shinsuke Sakai
Keyword(s):  
Shear Stress ◽  
Pathway Analysis ◽  
Activation Barrier ◽  
Silicon Crystal ◽  
Perfect Crystal ◽  
Dislocation Nucleation ◽  
Elastic Band ◽  
Perfect Dislocation ◽  
Band Method ◽  
First Time

AbstractTransition pathway sampling was carried out for homogeneous dislocation nucleation in perfect crystal Si. The sampling algorithm employed was Nudged Elastic Band method. Results obtained were compared with corresponding results for Cu. The stress and activation barrier ranges were found to be much higher for Si than those reported for Cu. The results also showed that while for lower values of resolved shear stress the dislocation embryo approaches that of a perfect dislocation, for higher resolved shear stress values the embryo is far from perfect. That is, the shear displacement of most particles is considerably less than the Burger’s vector. This investigation also demonstrated for the first time that Athermal shear stress for homogeneous dislocation nucleation in Si does not exist, as the crystal undergoes twinning at such high stresses.

Reaction pathway analysis for dislocation nucleation from a Ni surface step

2009 ◽  
Vol 106 (9) ◽  
pp. 093507 ◽  
Author(s):  
Shotaro Hara ◽  
Satoshi Izumi ◽  
Shinsuke Sakai
Keyword(s):  
Pathway Analysis ◽  
Reaction Pathway ◽  
Dislocation Nucleation ◽  
Surface Step ◽  
Reaction Pathway Analysis

Core element effects on dislocation nucleation in 3C–SiC: Reaction pathway analysis

2013 ◽  
Vol 79 ◽  
pp. 216-222 ◽  
Author(s):  
Yu Sun ◽  
Satoshi Izumi ◽  
Shinsuke Sakai ◽  
Kuniaki Yagi ◽  
Hiroyuki Nagasawa
Keyword(s):  
Pathway Analysis ◽  
Reaction Pathway ◽  
Dislocation Nucleation ◽  
Core Element ◽  
Reaction Pathway Analysis

Further understanding the premixed methane/hydrogen/air combustion by global reaction pathway analysis and sensitivity analysis

Fuel ◽  
2020 ◽  
Vol 259 ◽  
pp. 116190 ◽  
Author(s):  
Du Wang ◽  
Changwei Ji ◽  
Shuofeng Wang ◽  
Hao Meng ◽  
Zhe Wang ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Pathway Analysis ◽  
Reaction Pathway ◽  
Global Reaction ◽  
Reaction Pathway Analysis

Inhibition of Premixed Methane-Air Flames with CF3I

2009 ◽  
Vol 4 (3) ◽  
Author(s):  
Caimao Luo ◽  
Bogdan Dlugogorski ◽  
Eric Kennedy ◽  
Behdad Moghtaderi
Keyword(s):  
Sensitivity Analysis ◽  
Pathway Analysis ◽  
Laminar Flame ◽  
Computational Study ◽  
Reaction Pathway ◽  
Burning Velocity ◽  
Flame Velocity ◽  
Promoting Effect ◽  
Elementary Reactions ◽  
Reaction Pathway Analysis

This paper presents a systematic computational study of the inhibition of premixed flames of short chain hydrocarbons with CF3I, focusing on sensitivity analysis of the (normalized) burning velocity and reaction pathway analysis using the "iodine-flux" approach. A comprehensive kinetic mechanism was obtained by combining the GRI, hydrofluorocarbon and CF3I sub-mechanisms, and updating the rates of some of the elementary reactions. Calculations were performed using the PREMIX computer code in the CHEMKIN suite of computer codes. The updated mechanism yielded estimates of the normalized laminar burning velocities which concurs closely with published measurements. The sensitivity analysis resulted in a positive coefficient for CF3I + M ? CF3 + I + M, confirming the promoting effect of CF3I on the laminar flame velocity and is consistent with previous studies. Reaction pathways were drawn for stoichiometric, fuel-lean and fuel-rich flames doped with 1 and 2% of CF3I at atmospheric pressure. The reaction pathway analysis served to identify four major inhibition cycles, denoted as HI ? I ? HI, HI ? I ? I2 ? HI, HI ? I ? CH3I ? HI and HI ? I ? C2H5I ? HI. Furthermore, the paper developed a linear expression linking the normalized rate of heat release with the ratio of laminar burning velocities of mitigated and non-mitigated flames, and verified the efficacy of this expression for flames inhibited with CF3I.

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