Process of New Phase Nucleation in Alloys

Nucleation processes in phase transitions of a spin-reorientation type in real magnets are examined in the paper. The basic simulation of new-phase nuclei condensing on defects is chosen to be the magnetization distribution corresponding to a 0-degree domain wall. The numeric implementation of the corresponding variation problem for a sample of a finite thickness gives stable states of the considered magnetic heterogeneities and demonstrates that the structure and properties depend mainly on the defect parameters and the sample-quality factor. The obtained dependencies allow describing the behavior of the new-phase nuclei in the vicinity of the spin-reorientation phase transition quite consistently with the experimental data.

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On some aspects of crystallization process energetics, logistic new phase nucleation kinetics, crystal size distribution and Ostwald ripening

Journal of Applied Crystallography ◽

10.1107/s1600576717007105 ◽

2017 ◽

Vol 50 (4) ◽

pp. 1021-1027 ◽

Cited By ~ 7

Author(s):

Christo N. Nanev

Keyword(s):

Crystal Growth ◽

Size Distribution ◽

Crystal Size ◽

Ostwald Ripening ◽

Harmonic Oscillation ◽

Crystal Size Distribution ◽

Crystal Nucleation ◽

Nucleation Kinetics ◽

Phase Nucleation ◽

New Phase

Nucleation, nucleus number densities, and the respective supersaturation dependence, crystal growth and Ostwald ripening are reconsidered from the energetics perspective. Supersaturation-dependent critical nucleus sizes are calculated accordingly. It is argued that the logistic time-dependent nucleation resembles one period of a harmonic oscillation. The general conclusion is that a crystallizing system adapts to the distorting influence of the supersaturation imposed, and during crystal nucleation and growth, the system gradually consumes this supersaturation to reach a new equilibrium state at the end of Ostwald ripening (completely exhausted supersaturation). This is an indication that the system responds to the change in its energetic status according to the well known Le Châtelier–Braun principle. The extent to which the nucleation process affects the crystal size distribution (CSD) is also discussed. Slightly altered by the crystal growth, the CSD also preserves some trace of the nucleation stage shape during Ostwald ripening.

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Theory of Phase Transformations in the Mechanics of Solids and its Applications for Description of Fracture, Formation of Nanostructures and Thin Semiconductor Films Growth

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.528.145 ◽

2012 ◽

Vol 528 ◽

pp. 145-164 ◽

Cited By ~ 4

Author(s):

S.A. Kukushkin ◽

A.V. Osipov

Keyword(s):

Mechanics Of Solids ◽

Semiconductor Films ◽

Crystal Surfaces ◽

Mechanical Pressure ◽

Current State ◽

Fracture Formation ◽

Phase Nucleation ◽

Kinetic Criterion ◽

First Order Phase ◽

New Phase

The brief review of the current state of the theory of first-order phase transitions is given. The basic processes of nucleation and evolution of nanostructure ensembles on crystal surfaces are considered. The general equations describing nanoparticle size distribution, evolution of their average radius and density are deduced. The influence of mechanical pressure on nucleation and property of quantum dots and nanopores is considered. The equations describing new phase nucleation under condition of mechanical pressure caused by distinction in density of an old and new phase are resulted. The kinetic theory of micropore nucleation in solids under loading is described. The kinetic criterion is received of nucleation of micropores and microcracks in fragile solids under the influence of stretching pressure.

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