SOLUTE FIELD ACROSS DIFFUSE INTERFACE DURING TRANSIENT PROCESS OF BINARY ALLOYS SOLIDIFICATION IN PHASE FIELD MODE

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2768-2773
Author(s):  
ZHIJUN WANG ◽  
JINCHENG WANG ◽  
GENCANG YANG

The establishment of solute boundary layer is studied by using a quantitative phase field model during the initial transient stage of binary alloys solidification. Results reveal that the time-dependent solute distribution shows good agreements with the previous analytical results. The planar instability is discussed according to the time-dependent constitutional supercooling with different pulling velocities. Moreover, the critical pulling velocity of planar instability can be obtained by investigating the interface velocity of the critical instability with different pulling velocities.

2020 ◽  
pp. 2000162
Author(s):  
Chao Yang ◽  
Houbing Huang ◽  
Wenbo Liu ◽  
Junsheng Wang ◽  
Jing Wang ◽  
...  

Author(s):  
Naoki Takada

For interface-tracking simulation of two-phase flows in various micro-fluidics devices, the applicability of two versions of Navier-Stokes phase-field method (NS-PFM) was examined, combining NS equations for a continuous fluid with a diffuse-interface model based on the van der Waals-Cahn-Hilliard free-energy theory. Through the numerical simulations, the following major findings were obtained: (1) The first version of NS-PFM gives good predictions of interfacial shapes and motions in an incompressible, isothermal two-phase fluid with high density ratio on solid surface with heterogeneous wettability. (2) The second version successfully captures liquid-vapor motions with heat and mass transfer across interfaces in phase change of a non-ideal fluid around the critical point.


Author(s):  
Arne Claus Hansen-Dörr ◽  
Jörg Brummund ◽  
Markus Kästner

Abstract In this contribution, a variational diffuse modeling framework for cracks in heterogeneous media is presented. A static order parameter smoothly bridges the discontinuity at material interfaces, while an evolving phase-field captures the regularized crack. The key novelty is the combination of a strain energy split with a partial rank-I relaxation in the vicinity of the diffuse interface. The former is necessary to account for physically meaningful crack kinematics like crack closure, the latter ensures the mechanical jump conditions throughout the diffuse region. The model is verified by a convergence study, where a circular bi-material disc with and without a crack is subjected to radial loads. For the uncracked case, analytical solutions are taken as reference. In a second step, the model is applied to crack propagation, where a meaningful influence on crack branching is observed, that underlines the necessity of a reasonable homogenization scheme. The presented model is particularly relevant for the combination of any variational strain energy split in the fracture phase-field model with a diffuse modeling approach for material heterogeneities.


Author(s):  
T. Philippe ◽  
H. Henry ◽  
M. Plapp

At equilibrium, the shape of a strongly anisotropic crystal exhibits corners when for some orientations the surface stiffness is negative. In the sharp-interface problem, the surface free energy is traditionally augmented with a curvature-dependent term in order to round the corners and regularize the dynamic equations that describe the motion of such interfaces. In this paper, we adopt a diffuse interface description and present a phase-field model for strongly anisotropic crystals that is regularized using an approximation of the Willmore energy. The Allen–Cahn equation is employed to model kinetically controlled crystal growth. Using the method of matched asymptotic expansions, it is shown that the model converges to the sharp-interface theory proposed by Herring. Then, the stress tensor is used to derive the force acting on the diffuse interface and to examine the properties of a corner at equilibrium. Finally, the coarsening dynamics of the faceting instability during growth is investigated. Phase-field simulations reveal the existence of a parabolic regime, with the mean facet length evolving in t , with t the time, as predicted by the sharp-interface theory. A specific coarsening mechanism is observed: a hill disappears as the two neighbouring valleys merge.


1999 ◽  
Vol 60 (6) ◽  
pp. 7186-7197 ◽  
Author(s):  
Seong Gyoon Kim ◽  
Won Tae Kim ◽  
Toshio Suzuki

Author(s):  
Rakesh Dhote ◽  
Kamran Behdinan

In this paper, we study the dynamic thermo-mechanical behaviors of 3D shape memory alloy (SMA) nanostructures using the phase-field (PF) model. The PF model is based on the Ginzburg-Landau theory and requires a non-convex free energy function for an adequate description of the cubic-to-tetragonal martensitic phase transformations. We have developed a model that includes domain walls, treated as a diffuse interface, which leads to a fourth-order differential equation in a strain-based order parameter PF model. Arising numerical challenges have been overcome based on an isogeometric analysis (IGA) framework. Microstructure morphology evolution and consequent thermo-mechanical properties have been studied on SMA nanostructures of different geometries. The numerical results are in agreement with experimental observations. The developed coupled dynamic model has provided a better understanding of underlying microstructures and behaviors, which can be used for development of better SMA-based devices.


2000 ◽  
Vol 212 (3-4) ◽  
pp. 574-583 ◽  
Author(s):  
D.I. Popov ◽  
L.L. Regel ◽  
W.R. Wilcox

2016 ◽  
Vol 8 ◽  
pp. 9-18
Author(s):  
Jie Liao

A phase field model for binary alloy solidification with boundary interface intersection is developed. In the phase field model, the heat and solute conservation equations are appropriately modified to account for the presence of heat and solute rejection inside the diffuse interface, and a relaxation boundary condition for the phase field variable is introduced to balance the interface energy and boundary surface energy in the multiphase contact region. The thin interface asymptotic analysis is applied on the phase field model to yield the free interface problem with dynamic contact point condition.


2016 ◽  
Vol 9 ◽  
pp. 1-8
Author(s):  
Jie Liao

By incorporation the surface free energy in the free energy functional, a phase field model for solidification with boundary interface intersection is developed. In this model, the bulk equation is appropriately modified to account for the presence of heat diffusion inside the diffuse interface, and a relaxation boundary condition for the phase field variable is introduced to balance the interface energy and boundary surface energy in the multiphase contact region. The asymptotic analysis is applied on the phase field model to yield the free interface problem with dynamic contact point condition.


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