A review on the theory of stable dendritic growth

2021 ◽  
Vol 379 (2205) ◽  
pp. 20200325 ◽  
Author(s):  
Dmitri V. Alexandrov ◽  
Peter K. Galenko
Keyword(s):  
Dendritic Growth ◽  
Materials Science ◽  
Crystal Surface ◽  
Main Process ◽  
Sharp Interface Model ◽  
Mass Fluxes ◽  
Crystallization Conditions ◽  
Non Local ◽  
Polycrystalline Structures ◽  
Tip Velocity

This review article summarizes the main outcomes following from recently developed theories of stable dendritic growth in undercooled one-component and binary melts. The nonlinear heat and mass transfer mechanisms that control the crystal growth process are connected with hydrodynamic flows (forced and natural convection), as well as with the non-local diffusion transport of dissolved impurities in the undercooled liquid phase. The main conclusions following from stability analysis, solvability and selection theories are presented. The sharp interface model and stability criteria for various crystallization conditions and crystalline symmetries met in actual practice are formulated and discussed. The review is also focused on the determination of the main process parameters—the tip velocity and diameter of dendritic crystals as functions of the melt undercooling, which define the structural states and transitions in materials science (e.g. monocrystalline-polycrystalline structures). Selection criteria of stable dendritic growth mode for conductive and convective heat and mass fluxes at the crystal surface are stitched together into a single criterion valid for an arbitrary undercooling. This article is part of the theme issue ‘Transport phenomena in complex systems (part 1)’.

Thermodynamic Study of Crystal Growth Behavior Based on Structural Analysis of Chemical Bonds

2012 ◽  
Vol 602-604 ◽  
pp. 853-856 ◽  
Author(s):  
Xu Zhang ◽  
Hua Xie
Keyword(s):  
Crystal Growth ◽  
Structural Analysis ◽  
Materials Science ◽  
Growth Behavior ◽  
Crystal Formation ◽  
Chemical Bonds ◽  
Crystal Shape ◽  
Crystallization Conditions ◽  
Crystal Growth Behavior ◽  
The Ideal

Crystallization is a universal phenomenon in modern industry and has been developed into a core discipline. Investigation of the crystal formation has also increasingly become a vital subject in the field of materials science and technology. The crystal shape may be successfully varied by controlling its crystallization conditions, but there is far less understanding of how the crystal shape is modified. Thermodynamics of crystal growth behavior was developed to investigate the ideal shape of inorganic crystals on the basis of structural analysis of chemical bonds. The present work can help us to comprehend the crystal growth process and further guide the manipulation of crystal shape.

Dendritic Growth in Terrestrial and Microgravity Conditions

1994 ◽  
Vol 367 ◽  
Author(s):  
M.E. Glicksman ◽  
M.B. Koss ◽  
L.T. Bushnell ◽  
J.C. Lacombe ◽  
E.A. Winsa
Keyword(s):  
Dendritic Growth ◽  
Space Shuttle ◽  
Microgravity Environment ◽  
Radius Of Curvature ◽  
Thermal Gradients ◽  
Growth Data ◽  
Diffusion Solution ◽  
Microgravity Conditions ◽  
Space Shuttle Columbia ◽  
Tip Velocity

AbstractDendritic growth is the most ubiquitous form of crystal growth encountered when metals and alloys solidify under low thermal gradients. The growth of thermal dendrites in pure melts is generally acknowledged to be controlled by the diffusive transport of latent heat from the moving crystal-melt interface into its supercooled melt. However, this formulation is incomplete, and the physics of an additional selection rule, coupled to the transport solution, is necessary to predict uniquely the dendrite tip velocity and radius of curvature as a function of the supercooling. Unfortunately, experimental confirmation or evidence is ambiguous, because dendritic growth can be severely complicated by buoyancy induced convection. Recent experiments performed in the microgravity environment of the space shuttle Columbia (STS-62) quantitatively show that convection alters tip velocities and radii of curvature of succinonitrile (SCN) dendrites. In addition, these data can be used to evaluate how well the Ivantsov diffusion solution, coupled to a scaling constant, matches the dendritic growth data under microgravity conditions.

scholarly journals Surface Porosity of Natural Diamond Crystals after the Catalytic Hydrogenation

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1341
Author(s):  
Aleksei Chepurov ◽  
Valeri Sonin ◽  
Dmitry Shcheglov ◽  
Egor Zhimulev ◽  
Sergey Sitnikov ◽  
...  
Keyword(s):  
Catalytic Hydrogenation ◽  
Materials Science ◽  
Crystal Surface ◽  
Natural Diamond ◽  
Substrate Material ◽  
Diamond Surfaces ◽  
Diamond Crystals ◽  
Type Ia ◽  
Strong Resemblance ◽  
Natural Type

The study of diamond surfaces is traditionally undertaken in geology and materials science. As a sample material, two natural diamond crystals of type Ia were selected, and their luminescence and nitrogen state was characterized. In order to etch the surface catalytic hydrogenation was performed using Fe particles as an etchant. Micromorphology of the surface was investigated by scanning electron and laser confocal microscopy. It was demonstrated that etching occurred perpendicular to the crystal surface, with no signs of tangential etching. The average depth of caverns did not exceed 20–25 μm with a maximal depth of 40 μm. It is concluded that catalytic hydrogenation of natural type Ia diamonds is effective to produce a porous surface that can be used in composites or as a substrate material. Additionally, the comparison of results with porous microsculptures observed on natural impact diamond crystals from the Popigai astrobleme revealed a strong resemblance.

Nonconstant Tip Velocity in Microgravity Dendritic Growth

1999 ◽  
Vol 83 (15) ◽  
pp. 2997-3000 ◽  
Author(s):  
J. C. LaCombe ◽  
M. B. Koss ◽  
M. E. Glicksman
Keyword(s):  
Dendritic Growth ◽  
Tip Velocity

scholarly journals Application of X-ray topography to USSR and Russian space materials science

IUCrJ ◽  
2016 ◽  
Vol 3 (3) ◽  
pp. 200-210 ◽  
Author(s):  
I. L. Shul'pina ◽  
I. A. Prokhorov ◽  
Yu. A. Serebryakov ◽  
I. Zh. Bezbakh
Keyword(s):  
Crystal Growth ◽  
Materials Science ◽  
Perfect Crystal ◽  
Space Vehicles ◽  
X Ray Diffraction ◽  
Semiconductor Crystal ◽  
X Ray ◽  
Diffraction Imaging ◽  
Crystallization Conditions ◽  
Former Ussr

The authors' experience of the application of X-ray diffraction imaging in carrying out space technological experiments on semiconductor crystal growth for the former USSR and for Russia is reported, from the Apollo–Soyuz programme (1975) up to the present day. X-ray topography was applied to examine defects in crystals in order to obtain information on the crystallization conditions and also on their changes under the influence of factors of orbital flight in space vehicles. The data obtained have promoted a deeper understanding of the conditions and mechanisms of crystallization under both microgravity and terrestrial conditions, and have enabled the elaboration of terrestrial methods of highly perfect crystal growth. The use of X-ray topography in space materials science has enriched its methods in the field of digital image processing of growth striations and expanded its possibilities in investigating the inhomogeneity of crystals.

Cellulose nanocrystals by acid vapour: towards more effortless isolation of cellulose nanocrystals

2017 ◽  
Vol 202 ◽  
pp. 315-330 ◽  
Author(s):  
Marcel Lorenz ◽  
Stefan Sattler ◽  
Mehedi Reza ◽  
Alexander Bismarck ◽  
Eero Kontturi
Keyword(s):  
Cellulose Nanocrystals ◽  
Materials Science ◽  
Crystal Surface ◽  
Acid Catalyst ◽  
Strong Acid ◽  
Degree Of Polymerization ◽  
Full Potential ◽  
Cellulose Fibres ◽  
Formidable Challenge ◽  
Pre Treatment

Cellulose nanocrystals (CNCs) are topical in materials science but their full potential is yet to be fulfilled because of bottlenecks in the production: the process consumes huge amounts of water, recycling the strong acid catalyst is difficult, and purification steps are cumbersome, particularly with lengthy dialysis. Production of CNCs with HCl vapour overcomes many of these difficulties but the dispersion of CNCs from the already hydrolysed fibre matrix is a formidable challenge. This study is a fundamental effort to explore very basic means to facilitate CNC dispersion from cotton linter fibres (filter paper), hydrolysed to levelling off degree of polymerization by HCl vapour. The introduction of carboxylic groups on the cellulose crystal surface proved the most efficient method to alleviate dispersion with good yields (ca. 50%) and a provisional possibility to tune the CNC length. By contrast, attempts to directly disperse untreated hydrolysed fibres in various organic solvents and aqueous surfactant solutions were unsuccessful. The results showed that hydrolysis of native cellulose fibres by HCl vapour is indeed a viable method for producing CNCs but it has more potential as a pre-treatment step rather than a full-fledged process on its own.

Interfacial wave theory of two-dimensional dendritic growth with anisotropy of surface tension

1991 ◽  
Vol 69 (7) ◽  
pp. 789-800 ◽  
Author(s):  
Jian-Jun Xu
Keyword(s):  
Surface Tension ◽  
Dendritic Growth ◽  
Wave Theory ◽  
Two Dimensional ◽  
Interfacial Wave ◽  
Selection Condition ◽  
Tip Velocity

In this paper, we consider two-dimensional dendritic growth from pure melt with inclusion of the anisotropy of surface tension. The interfacial wave theory previously established for axisymmetric dendritic growth is extended to this case. The results show that the effect of the anisotropy of surface tension on the selection condition of the tip velocity is not significant.

scholarly journals Thermo-solutal and kinetic modes of stable dendritic growth with different symmetries of crystalline anisotropy in the presence of convection

2018 ◽  
Vol 376 (2113) ◽  
pp. 20170215 ◽  
Author(s):  
Dmitri V. Alexandrov ◽  
Peter K. Galenko ◽  
Lyubov V. Toropova
Keyword(s):  
Convective Flow ◽  
Materials Science ◽  
Selection Criterion ◽  
Theme Issue ◽  
Stable Mode ◽  
Theoretical Approaches ◽  
Solvability Criterion ◽  
State Growth ◽  
Forced Convective Flow ◽  
Tip Velocity

Motivated by important applications in materials science and geophysics, we consider the steady-state growth of anisotropic needle-like dendrites in undercooled binary mixtures with a forced convective flow. We analyse the stable mode of dendritic evolution in the case of small anisotropies of growth kinetics and surface energy for arbitrary Péclet numbers and n -fold symmetry of dendritic crystals. On the basis of solvability and stability theories, we formulate a selection criterion giving a stable combination between dendrite tip diameter and tip velocity. A set of nonlinear equations consisting of the solvability criterion and undercooling balance is solved analytically for the tip velocity V and tip diameter ρ of dendrites with n -fold symmetry in the absence of convective flow. The case of convective heat and mass transfer mechanisms in a binary mixture occurring as a result of intensive flows in the liquid phase is detailed. A selection criterion that describes such solidification conditions is derived. The theory under consideration comprises previously considered theoretical approaches and results as limiting cases. This article is part of the theme issue ‘From atomistic interfaces to dendritic patterns’. This article is part of the theme issue ‘From atomistic interfaces to dendritic patterns’.

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