Interface Instabilities During Laser Melting of Thin Films

1990 ◽  
Vol 43 (5S) ◽  
pp. S70-S75 ◽  
Author(s):  
G. B. McFadden ◽  
S. R. Coriell ◽  
L. N. Brush ◽  
K. A. Jackson
Keyword(s):  
Thermal Field ◽  
Numerical Solutions ◽  
Boundary Integral ◽  
Radiative Heating ◽  
Liquid Interfaces ◽  
Two Phase ◽  
Lamellar Structures ◽  
Solid Liquid ◽  
Boundary Integral Representation ◽  
Liquid And Solid Phases

Thin silicon films on a cooled substrate are often found to develop two-phase lamellar structures upon radiative heating. Jackson and Kurtz developed a two-dimensional model for the process in which the heated film consists of alternating parallel bands of liquid and solid phases separated by straight solid-liquid interfaces. To understand the cellular or dendritic structures that sometimes are observed in these interfaces, they also performed a linearized morphological stability analysis and obtained the conditions for the growth or decay of infinitesimal perturbations to the interface. In this work we extend that analysis to finite amplitudes by developing a boundary integral representation of the thermal field, and obtain numerical solutions for nonplanar solid-liquid interfaces.

The boundary integral equation for curved solid/liquid interfaces propagating into a binary liquid with convection

2021 ◽  
Author(s):  
Ekaterina Titova ◽  
Dmitri Alexandrov
Keyword(s):  
Integral Equation ◽  
Boundary Integral Equation ◽  
Boundary Integral ◽  
Boundary Integral Method ◽  
Curvilinear Coordinates ◽  
Forced Flow ◽  
Function Technique ◽  
Liquid Interfaces ◽  
Convective Boundary ◽  
Solid Liquid

Abstract The boundary integral method is developed for unsteady solid/liquid interfaces propagating into undercooled binary liquids with convection. A single integrodifferential equation for the interface function is derived using the Green function technique. In the limiting cases, the obtained unsteady convective boundary integral equation (CBIE) transforms into a previously developed theory. This integral is simplified for the steady-state growth in arbitrary curvilinear coordinates when the solid/liquid interface is isothermal (isoconcentration). Finally, we evaluate the boundary integral for a binary melt with a forced flow and analyze how the melt undercooling depends on P\'eclet and Reynolds numbers.

scholarly journals The boundary integral theory for slow and rapid curved solid/liquid interfaces propagating into binary systems

2018 ◽  
Vol 376 (2113) ◽  
pp. 20170218 ◽  
Author(s):  
Peter K. Galenko ◽  
Dmitri V. Alexandrov ◽  
Ekaterina A. Titova
Keyword(s):  
Binary Systems ◽  
Computational Modelling ◽  
Selection Criterion ◽  
Type Equation ◽  
Boundary Integral ◽  
Boundary Integral Method ◽  
Isotropic Case ◽  
Liquid Interfaces ◽  
Stationary Growth ◽  
Solid Liquid

The boundary integral method for propagating solid/liquid interfaces is detailed with allowance for the thermo-solutal Stefan-type models. Two types of mass transfer mechanisms corresponding to the local equilibrium (parabolic-type equation) and local non-equilibrium (hyperbolic-type equation) solidification conditions are considered. A unified integro-differential equation for the curved interface is derived. This equation contains the steady-state conditions of solidification as a special case. The boundary integral analysis demonstrates how to derive the quasi-stationary Ivantsov and Horvay–Cahn solutions that, respectively, define the paraboloidal and elliptical crystal shapes. In the limit of highest Péclet numbers, these quasi-stationary solutions describe the shape of the area around the dendritic tip in the form of a smooth sphere in the isotropic case and a deformed sphere along the directions of anisotropy strength in the anisotropic case. A thermo-solutal selection criterion of the quasi-stationary growth mode of dendrites which includes arbitrary Péclet numbers is obtained. To demonstrate the selection of patterns, computational modelling of the quasi-stationary growth of crystals in a binary mixture is carried out. The modelling makes it possible to obtain selected structures in the form of dendritic, fractal or planar crystals. This article is part of the theme issue ‘From atomistic interfaces to dendritic patterns’.

Two-Phase Thermal Metamaterial

2020 ◽  
Author(s):  
Zifu Xu ◽  
Longqiu Li ◽  
Jiaxin Li
Keyword(s):  
Heat Transfer ◽  
Thermal Field ◽  
Gradient Field ◽  
Transfer System ◽  
Solid Materials ◽  
Two Phase ◽  
Single Function ◽  
Media Condition ◽  
Heat Transfer System ◽  
Solid Liquid

Abstract The capability of thermal metamaterials is required from single function to multifunction under different external heat conditions. The methods to develop thermal materials by simple structural transformations have been explored. While, the components of traditional thermal metamaterial are mainly set as solid materials, which is difficult to change the composition of materials, such as recombing and fixing the spatial position of material, because of material rigidity. Therefore, the potential of thermal materials is limited. Liquid has fluidity in spatial structure, for which the efficient combination of solid-liquid materials provides an avenue for dynamically modeling thermal field. Herein, we propose the concept of two-phase thermal metamaterial, which is switchable by microscale elements. On one side, we develop a switchable thermal meta-unit manipulated by micro-element under the gradient field and explore the process of heat transfer by focusing on radiation and conduction under translucent media condition. Otherwise, we propose a method to achieve a non-reciprocal heat transfer system by the design of two-phase media. The propose of two-phase thermal metamaterials set a general background for a variety of applications for complex conditions.

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