Effect of the Nitriding Potential on the Layer Growth Kinetics of Nitrided Pure Iron

2006 ◽  
Vol 258-260 ◽  
pp. 172-175
Author(s):  
Mourad Keddam
Keyword(s):  
Kinetic Model ◽  
Growth Kinetics ◽  
Pure Iron ◽  
Layer Growth ◽  
Iron Nitrides ◽  
Nitrogen Diffusion ◽  
Gas Nitriding ◽  
Simulation Results ◽  
Nitriding Potential ◽  
Kinetics Of

In this work, an approach of reactive nitrogen diffusion is presented and applied to the iron gas nitriding process. A kinetic model based on Fick's laws is used to simulate the layer growth kinetics of a biphase configuration composed of ε and γ’ iron nitrides grown on the pure iron substrate. This diffusional approach, under certain assumptions, reveals the influence of the nitriding potential on the layer growth kinetics during the gas nitriding of pure iron. Some simulation results are presented and discussed.

scholarly journals Growth kinetics of the compound layers: Effect of the nitriding potential

2009 ◽  
Vol 2 (3) ◽  
pp. 1399-1403 ◽  
Author(s):  
M. Keddam ◽  
B. Bouarour ◽  
R. Kouba ◽  
R. Chegroune
Keyword(s):  
Growth Kinetics ◽  
Nitriding Potential ◽  
Kinetics Of

The Growth Kinetics and Shape Evolution of Precipitates Growing by the Ledge Mechanism

1991 ◽  
Vol 237 ◽  
Author(s):  
Masato Enomoto ◽  
George Spanos ◽  
Robert A. Masumura
Keyword(s):  
Growth Kinetics ◽  
Diffusion Field ◽  
Shape Evolution ◽  
Field Interaction ◽  
Relative Growth ◽  
Nucleation Sites ◽  
Simulation Results ◽  
Kinetics Of ◽  
Ledge Mechanism ◽  
Evolution Of Precipitates

ABSTRACTThe characteristics of ledge growth of precipitates are investigated by a previously developed finite-difference computer model. The plate lengthening simulation results which incorporate measured ledge heights and spacings are in reasonable agreement with the observed lengthening behavior of plates in Fe-C alloys. The simulation which takes into account the diffusion field interaction among multiple precipitates shows that a variety of precipitate morphologies actually observed can possibly be formed solely by the change in the extent of diffusion field overlap among ledges and/or neighboring precipitates. This overlap is in turn caused by changes in the solute supersaturation, distribution of ledge nucleation sites and ledge nucleation rates. A brief discussion is made of the relative growth kinetics of ledged and disordered interfaces.

A simple model for the growth kinetics of Fe2B iron boride on pure iron substrate

2010 ◽  
Vol 256 (10) ◽  
pp. 3128-3132 ◽  
Author(s):  
M. Keddam ◽  
M. Ortiz-Domínguez ◽  
I. Campos-Silva ◽  
J. Martínez-Trinidad
Keyword(s):  
Simple Model ◽  
Growth Kinetics ◽  
Pure Iron ◽  
Iron Boride ◽  
Kinetics Of

Growth kinetics of MgB2 layer and interfacial MgO layer during ex situ annealing of amorphous boron film

2004 ◽  
Vol 19 (10) ◽  
pp. 3081-3089 ◽  
Author(s):  
Hyun-Mi Kim ◽  
Sung-Soo Yim ◽  
Ki-Bum Kim ◽  
Seung-Hyun Moon ◽  
Young-Woon Kim ◽  
...  
Keyword(s):  
Growth Kinetics ◽  
Interfacial Layer ◽  
Surface Reaction ◽  
Layer Growth ◽  
Ex Situ ◽  
Amorphous Boron ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Kinetics Of ◽  
Rough Surface Morphology

This paper describes the growth kinetics of an interfacial MgO layer as well as those of an MgB2 layer during ex situ annealing of the evaporated amorphous boron (a-B) film under Mg vapor overpressure. A thin MgO layer is formed at the interface between a-B and Al2O3 substrate before the formation of crystalline MgB2 layer and the interfacial layer is epitaxially related with Al2O3 substrate (MgO (111)[110] // Al2O3 (0001)[1100]). The interfacial MgO layer continues to grow during the annealing, and its apparent growth rate is about 0.1 nm/min. The analysis of MgB2 layer growth kinetics using cross-sectional transmission electron microscopy reveals that there exist two distinct growth fronts at both sides of an MgB2 layer. The growth kinetics of the lower MgB2 layer obeys the parabolic rate law during the entire annealing time. The growth of the upper MgB2 layer is controlled by the surface reaction between out-diffused boron and Mg vapor up to 10 min, resulting in a rough surface morphology of MgB2 layer. By considering the mass balance of Mg and boron during ex situ annealing, we obtained the diffusivities of Mg and boron in MgB2 layer which were in the same order range of approximately 10−12 cm2/s.

scholarly journals GAS NITRIDING WITH DEEP CRYOGENIC TREATMENT OF HIGH-SPEED STEEL

2018 ◽  
Vol 24 (2) ◽  
pp. 187 ◽  
Author(s):  
David Hradil ◽  
Michal Duchek ◽  
Taťána Hrbáčková ◽  
Aleksander Ciski
Keyword(s):  
High Speed ◽  
Conventional Treatment ◽  
Cryogenic Treatment ◽  
High Speed Steel ◽  
Iron Nitrides ◽  
Nitrogen Diffusion ◽  
Deep Cryogenic Treatment ◽  
Gas Nitriding ◽  
Subsurface Layers ◽  
Quenching And Tempering

<p class="AMSmaintext"><span lang="EN-GB">Nitriding with subsequent heat treatment in combination with deep cryogenic treatment (DCT) produces nitrided layers with specific properties. Layers with unique properties result from the dissolution of subsurface layers of iron nitrides and subsequent nitrogen diffusion into the substrate during austenitisation. Fine precipitates of carbonitrides eventually form during DCT and tempering. Intermediate deep cryogenic treatment was performed between the quenching and tempering steps. This work is based on comparing nitrided layers obtained using conventional treatment parameters with nitrided layers from novel processes. The experimental material was DIN 1.3343 (Czech Standard 41 9830) high-speed steel. Several treatment methods were compared in terms of the resulting hardness and metallographic characteristics.</span></p><p> </p>

Experiments and modeling study on growth behavior of Cr-nitrides formed on electroplated hard Cr during ion-nitriding

2003 ◽  
Vol 18 (4) ◽  
pp. 861-867 ◽  
Author(s):  
J. Y. Eom ◽  
V. Shankar Rao ◽  
H. S. Kwon ◽  
K. S. Nam ◽  
S. C. Kwon
Keyword(s):  
Growth Kinetics ◽  
Diffusion Constant ◽  
Nitride Layer ◽  
Growth Behavior ◽  
Computer Simulation Model ◽  
Nitrogen Diffusion ◽  
Nitriding Temperature ◽  
Ion Nitriding ◽  
Nitride Layers ◽  
Kinetics Of

The structure and composition of Cr-nitrides formed on an electroplated hard Cr layer during an ion-nitriding process were analyzed, and its growth kinetics was examined as a function of the ion-nitriding temperature and time to establish a computer simulation model for the prediction of growth behavior of the Cr-nitride layer. The Cr-nitrides formed during the ion-nitriding at 550–770 °C were composed of outer CrN and inner Cr2N layers. A nitrogen diffusion model in the multilayer, based on fixed-grid finite difference method, was applied to simulate the growth kinetics of Cr-nitride layers. By measuring the thickness of Cr-nitride layers as a function of ion-nitriding temperature and time, the activation energy (Q) and nitrogen diffusion constant (Do) were determined for growth of CrN and Cr2N; the result was applied to simulate the growth kinetics of Cr-nitride layers, and reasonable good agreement was obtained with the experimental results.

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