Kinetics of chemical short-range ordering in liquids and diffusion-controlled reactions

We review the results of our Monte Carlo simulation studies carried out within the past two decades in the area of atomic-migration-controlled phenomena in intermetallic compounds. The review aims at showing the high potential of Monte Carlo methods in modelling both the equilibrium states of the systems and the kinetics of the running processes. We focus on three particular problems: (i) the atomistic origin of the complexity of the ‘order-order’ relaxations in γ’-Ni3Al; (ii) surface-induced ordering phenomena in γ-FePt and (iii) ‘order—order’ kinetics and self-diffusion in the ‘triple-defect’ β-NiAl. The latter investigation demonstrated how diverse Monte Carlo techniques may be used to model the phenomena where equilibrium thermodynamics interplays and competes with kinetic effects.

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Refinement of Size Distributions for Primary Crystallizations

MRS Proceedings ◽

10.1557/proc-481-213 ◽

1997 ◽

Vol 481 ◽

Author(s):

E. Pineda ◽

T. Pradell ◽

D. Crespo ◽

N. Clavaguera ◽

J. ZHU ◽

...

Keyword(s):

Grain Size ◽

Metastable Phase ◽

Primary Crystallization ◽

Controlled Growth ◽

Diffusion Controlled ◽

Average Grain Size ◽

Soft Impingement ◽

Single Grain ◽

Kinetics Of ◽

And Diffusion

ABSTRACTThe microstructure developed in primary crystallizations is studied under realistic conditions. The primary crystallization of an amorphous alloy is modeled by considering the thermodynamics of a metastable phase transition and the kinetics of nucleation and crystal growth under isothermal annealing. A realistic growth rate, including an interface controlled growth at the beginning of the growth of each single grain and diffusion controlled growth process with soft impingement afterwards is considered. The reduction in the nucleation rate due to the compositional change in the remaining amorphous matrix is also taken into account. The microstructures developed during the transformation are obtained by using the Populational KJMA method, from the above thermodynamic and kinetic factors. Experimental data of transformed fraction, grain density, average grain size, grain size distribution and other related parameters obtained from annealed metallic glasses are modeled.

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Susceptibility to Severe PWSCC (primary water stress corrosion cracking) of LTMA (low temperature mill anneal) Alloy 600

Korean Journal of Metals and Materials ◽

10.3365/kjmm.2020.58.12.815 ◽

2020 ◽

Vol 58 (12) ◽

pp. 815-821

Author(s):

Sung Soo Kim ◽

Jung Jong Yeob ◽

Young Suk Kim

Keyword(s):

Water Stress ◽

Low Temperature ◽

Stress Corrosion Cracking ◽

Short Range ◽

Alloy 600 ◽

Lattice Contraction ◽

Short Range Ordering ◽

Mill Anneal ◽

Primary Water ◽

Kinetics Of

It has been proposed that a primary water stress corrosion cracking (PWSCC) in pressurized water reactor (PWR) is governed by a lattice contraction due to a short range ordering reaction in Alloy 600. This leads researcher to think that the kinetics of lattice contraction may control a susceptibility of PWSCC in Alloy 600. A lattice variation with ordering treatment at 400 <sup>o</sup>C was systematically investigated using high resolution neutron diffraction(HRPD) in high temperature mill anneal (HTMA), low temperature mill anneal (LTMA), and sensitized (SEN) Alloy 600. The results showed that ordering treatment caused an isotropic lattice contraction due to short range ordering (SRO) reaction. The lattice contractions of (111) plane are saturated to be 0.04% in 4 to 1500 hours at 400 <sup>o</sup>C according to prior treatment condition. The lattice contraction in the magnitude of 0.03% of (111) plane in LTMA Alloy 600 is faster by 8 times and 66 times than that of SEN and HTMA, respectively. This fact may explain why the LTMA is most susceptible to PWSCC through of kinetics of lattice contraction in Alloy 600. Thus, it is possible to conclude that the susceptibility of Alloy 600 to PWSCC is governed by the kinetics of (111) lattice contraction.

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Chapter 11. KINETICS OF COARSENING AND DIFFUSION-CONTROLLED MINERAL GROWTH

Contact Metamorphism ◽

10.1515/9781501509612-014 ◽

1991 ◽

pp. 507-582 ◽

Cited By ~ 24

Author(s):

Raymond L. Joesten

Keyword(s):

Mineral Growth ◽

Diffusion Controlled ◽

Kinetics Of ◽

And Diffusion

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Influence of Al concentration on the kinetics of short-range ordering in α-CuAl

phys stat sol (a) ◽

10.1002/pssa.2211400204 ◽

1993 ◽

Vol 140 (2) ◽

pp. 329-340 ◽

Cited By ~ 6

Author(s):

T. Doppler ◽

W. Pfeiler

Keyword(s):

Short Range ◽

Short Range Ordering ◽

Kinetics Of

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Suppressed kinetics of short range ordering at low temperatures

The Journal of Chemical Physics ◽

10.1063/1.453220 ◽

1987 ◽

Vol 87 (3) ◽

pp. 1604-1609 ◽

Cited By ~ 32

Author(s):

B. Fultz

Keyword(s):

Low Temperatures ◽

Short Range ◽

Short Range Ordering ◽

Kinetics Of

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Thermal and Mechanical Stability of Polycrystalline Nanowires

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.264.133 ◽

2007 ◽

Vol 264 ◽

pp. 133-140

Author(s):

Leonid Klinger ◽

Eugen Rabkin

Keyword(s):

Plastic Deformation ◽

Applied Load ◽

Mechanical Stability ◽

Deformation Behaviour ◽

High Yield ◽

Morphological Stability ◽

Diffusion Controlled ◽

Kinetics Of ◽

And Diffusion ◽

Shape Changes

We considered a polycrystalline cylindrical nanowire with bamboo microstructure strained uniaxially by an external load. Our molecular dynamic computer simulations demonstrated that grain boundary grooving plays an important role in determining the morphological stability of nanowires. Also, an exceptionally high yield stress of nanowires emphasizes the importance of diffusion in their plastic deformation under applied load. We formulated a phenomenological diffusion-based model describing morphological stability and diffusion-controlled deformation behaviour of polycrystalline nanowires. The kinetics of the shape changes was calculated numerically.

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