DISSERTATIONS AND ABSTRACTS OF THESES
ABSTRACT OF DOCTORAL THESIS -
DOCTOR OF SCIENCES (HABILITATED)
Shirinyan A. S.
The change of the physical and chemical properties of nanomaterials
in size-dependent first order phase transformations. – Manuscript.
Dissertation (thesis) for scientific degree of doctor of physical and
mathematical sciences by speciality 01.04.07 – solid state physics.
// Taras Shevchenko Kyiv National University of the
Ministry of Education and Science, Youth and Sport of Ukraine,
Kyiv, 2012, 368p (36p).
Change of properties of solid nanomaterials in
first order phase transformations is
Correlations between the properties of the new
and size of nanomaterials are defined.
Phase diagrams of binary nanosystems are
The author shows that solidus and liquidus
do not correlate to thermodynamic equilibrium.
The scientific definitions of solid state
first order phase transformations with concentration redistribution
to nanosystems. The processes of multicomponent
thermal cycling under the first order phase transformation are
We offer the proportion for thermal hysteresis
of α-Fe→γ-Fe→α-Fe transformations
of Fe nanopowders within the cycling
temperature interval 800 K-1450 K.
The possibility of concentration
‘self-saturation’ effect in kinetics
of phase separation of metastable binary alloy under the constant
external conditions is shown.
The size dependence for potential energy of
the interaction between neighbour atoms
in nanomaterials at zero temperatures and for
diffusion coefficients of atoms
in nanophases is substantiated. The result has
been applied for thermodynamic calculations
and designing diagrams of metallic Bi-Sn and
Bi-Pb nanosystems phases.
The problem of new nanosized phase growth
kinetics in а binary diffusion couple
is solved taking into account the size
dependence of the diffusion coefficients.
It is shown that the growth rate index for the
new nanophase layer may be nonmonotonous in time.
Keywords: thermodynamics, kinetics, phase
transformation, size effect, phase diagram,
thermal hysteresis, self-saturation, atomic
interaction, reactive diffusion.
ABSTRACT OF PH D THESIS - CANDIDATE OF SCIENCES
Shirinyan A. S.
Influence of the system size and of concentration gradient
in the diffusion zone on thermodynamics of nucleation and decomposition.
– Manuscript. / Dissertation (abstract) for a Ph. D. degree in physics
and mathematics sciences by speciality 01.04.07. – Solid state physics.
// Kharkov National Karazin University, Kharkov, 2001, 191p (20p).
A thermodynamics of multiple nucleation and decomposition in alloys,
in fine-grained systems and in the binary diffusion couple
during the reactive diffusion in the initial concentration gradient field is considered.
A thermodynamics of simultaneous nucleation of many nuclei and of separation
in amorphous alloy is considered. The quantitative analysis of nucleation of one nucleus
and decomposition in small isolated inorganic particles is presented.
It is shown that there exist three possibilities: phase separation,
prohibition of decomposition and metastable state of alloy.
Problem is solved taking into account a compositional depletion
of the parent phase. The detailed analysis of the competitive nucleation
of two intermediate phases and separation
in small particle has been made. The possibility of formation and total stabilization
of metastable Al3Li1 phase instead of stable Al1Li1 phase
in small particles of Al-5-50 ат.% Li alloys is demonstrated.
Nucleation of intermediate phase during the reactive diffusion
in the binary diffusion couple due to fluctuation,
which takes into account the optimized redistribution
of composition in the diffusion zone, is considered.
Analysis of all modes (longitudinal, transversal, polymorphous)
of nucleation in binary diffusion couple has been modified.
For all modes of nucleation formulas of dependencies
of the Gibbs free energy changing from volume,
form and concentration gradient have been obtained.
nucleus, depletion, Gibbs free energy, size effect, competitive separation,
phase diagram, gradient of concentration, nucleation modes.