Abhik ChoudhuryIndian Institute of Science | IISC · Department of Materials Engineering
Abhik Choudhury
PhD
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60
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Publications (60)
![Undercooling vs. spacing (ΔT-λ\documentclass[12pt]{minimal}...](publication/354064055/figure/fig1/AS:1059831700008960@1629694976095/Undercooling-vs-spacing-DT-ldocumentclass12ptminimal-usepackageamsmath_Q320.jpg)
![Steady-state morphology for Dl=(2,1)\documentclass[12pt]{minimal}...](publication/354064055/figure/fig5/AS:1059831708397568@1629694978225/Steady-state-morphology-for-Dl2-1documentclass12ptminimal-usepackageamsmath_Q320.jpg)
In this paper, we investigate three-phase eutectic growth during thin-film directional solidification of a model symmetric ternary eutectic alloy. In contrast to two-phase eutectics that have only a single possibility, αβαβ…\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage...
Eutectic solidification in ternary systems is a complex process involving the interaction of several material and process parameters resulting in the formation of intriguing patterns. Recently, we have observed the evolution of complex patterns in the ternary Ag-Cu-Sb eutectic system consisting of two intermetallic phases (Ag3Sb, Cu2Sb), along with...
In this paper, we investigate three-phase eutectic growth during thin-film directional solidification of a model symmetric ternary eutectic alloy. In contrast to two-phase eutectics that have only a single possibility, ${\alpha}{\beta}{\alpha}{\beta}$..., as the growth pattern, during three-phase eutectic growth infinite possibilities exist. Here,...
In this paper, we study three dimensional microstructural evolution in a symmetric ternarythree-phase eutectic alloy using phase-field simulations under directional solidification condi-tions. While previous studies have explored the influence of volume fractions, difference insolid-liquid interfacial energies, velocity changes, etc. on the microst...
In this paper, we have formulated a phase-field model based on the grand-potential functional for the simulation of precipitate growth in the presence of coherency stresses. In particular, we study the development of dendrite-like patterns arising out of diffusive instabilities during the growth of a precipitate in a supersaturated matrix. Here, we...
Organic photovoltaics (OPVs) have held on to the race for providing a sustainable source of energy for more than two decades, and ternary OPVs have emerged as a promising candidate for harnessing solar energy. While the ternary OPVs have potential, optimization of the process parameters, particularly for deriving active-layer morphologies with high...
In this paper, we explore the morphological evolution during two-phase growth in the Sn-Zn
eutectic system, which has a particularly low volume fraction of the minority Zn phase. The
reason for this choice is its exotic nature, as even with such a low volume fraction, the reported morphology is ‘‘broken-lamellar,’’ in contrast to the usually expect...
Eutectic solidification gives rise to a wide range of microstructures. A commonly observed
morphology is the periodic arrangement of lamellar plates with well-defined orientations of the solid–solid interface in a given eutectic grain. It is typically believed that this form of
morphology develops due to the presence of solid–solid interfacial ener...
In this paper, we formulate a phase-field model for the computation of equilibrium configurations of multiple phases that arise out of a solid-state precipitate reaction, in the presence of coherency stresses. Here, we utilize the phase-field framework to minimize the sum of the elastic and the interfacial energies for a given volume of the precipi...
Eutectics are self-organized composite materials that exhibit a wide variety of microstructural features. Besides intrinsic materials properties like interfacial energies or diffusivities as well as the nature of the phase diagrams, the process parameters such as magnitude and orientation of the temperature gradient as well as the velocity of the g...
Organic photovoltaics (OPVs) can potentially provide a cost-efficient means of harnessing solar energy. However, optimum OPV performance depends on understanding the process–structure–property (PSP) correlation in organic semiconductors. In the working of bulk-heterojunction OPVs, the morphology plays a crucial role in device performance. In order...
Very thin metallic films are susceptible to dewetting upon thermal excursions, resulting in fragmentation and hence loss of structural integrity. Herein, 15 to 55 nm thick Cu films deposited on a Si substrate were isothermally annealed at 400 to 700 °C inside a scanning electron microscope operating in the high vacuum mode and the ensuing dewetting...
In this paper, we formulate a phase-field model for the computation of equilibrium configurations of multiple phases that arise out of a solid-state precipitate reaction, in the presence of coherency stresses. Here, we utilize the phase-field framework to minimize the sum of the elastic and the interfacial energies for a given volume of the precipi...
Coherency misfit stresses and their related anisotropies are known to influence the equilibrium shapes of precipitates. Additionally, mechanical properties of the alloys are also dependent on the shapes of the precipitates. Therefore, in order to investigate the mechanical response of a material which undergoes precipitation during heat treatment,...
Grain-boundary migration, void formation as well as associated hillock formation are important mechanisms which lead
to the failure of interconnects in the microelectronic packages. An understanding of the underlying physics of each of
the phenomena can allow better design of interconnects. In this paper, we formulate a new phase-field model based o...
Coherency misfit stresses and their related anisotropies are known to influence the equilibrium shapes of precipitates. Additionally, mechanical properties of the alloys are also dependent on the shapes of the precipitates. Therefore, in order to investigate the mechanical response of a material which undergoes precipitation during heat treatment,...
Phase-field modeling has developed as an important tool in investigating microstructural evolution in a variety of phenomena such as solidification, solid-state phase transformations, electrochemical reactions, mechanical deformation and fracture processes, and also domain evolution in ferro-electric materials. Given the strong thermodynamic basis...
We have used a phase field model to study destabilization of cylindrical pores in a polycrystalline membrane; a key feature in the model is that it incorporates surface diffusion as the mechanism for mass transport. Using a model system in which a cylindrical pore runs through a material in which all the grain boundaries (GBs) are perpendicular to...
In multi-component systems, during diffusion-controlled growth of a precipitate from a supersaturated matrix, differential diffusivities lead to a selection of tie-line compositions different from the thermodynamic tie-line containing the alloy composition. In this paper, we address the multi-component version of the growth problem by extending Zen...
Instability of a binary eutectic solidification front to morphological perturbations due to rejection of a ternary impurity leads to the formation of eutectic colonies. Whereas, the instability dynamics and the resultant mi- crostructural features are reasonably well understood for isotropic systems, several experimental observations point to the e...
A straight-forward extension of the Jackson-Hunt theory for directionally solidifying multi-phase growth where the number of components exceeds the number of solid phases becomes difficult on account of the absence of the required number of equations to determine the boundary layer compositions ahead of the interface. In this paper, we therefore re...
Diffusive instabilities of the Mullins-Sekerka type are one of the principal mechanisms through which microstructures form during solidification. In this study, we perform a linear stability analysis for the perturbation of a planar interface, where we derive analytical expressions to characterize the dispersion behavior in multi-component alloys u...
Eutectic solidification gives rise to a number of distinct microstructure patterns that might include lamella, rods and labyrinths in binary alloys. However, as the number of phases and components increases, the number of possible patterns that might be obtained during bulk solidification also become larger. While the morphological attributes of bi...
We have used a phase field model to study Rayleigh instability driven evolution of a cylindrical pore. The key feature in the model is its ability to incorporate surface diffusion as the mechanism for mass transport. We first benchmark our model with analytical results for growth rates of sinusoidal perturbations imposed on the surface of a cylindr...
The stereology, variant distribution and coarsening behavior of semicoherent α(hcp) precipitates in a β(bcc) matrix of a Ti5553 alloy has been analyzed, and a dominant 3-variant cluster has been observed in which the variants are related to each other by an axis-angle pair <11 0 >/ 60°. Shape and spatial distribution independent elastic self and in...
Ternary eutectics, where three phases form simultaneously from the melt, present an opportunity to study the fundamental science of microstructural pattern formation during the process of solidification. In this paper we investigate these phenomena, both experimentally and by phase-field simulations. The aim is to develop necessary characterisation...
Understanding the role of solute diffusivities in equilibrium tie-line selection during growth of a second phase in ternary and higher multicomponent two phase alloys is an important problem due to the strong dependence of mechanical properties on compositions. In this paper, we derive analytical expressions for predicting tie-lines and composition...
In this article, we review the progress in the field of application of phase-field models for simulating electrochemical phenomena such as etching, electro-deposition, electromigration, intercalation etc. As we will see the present models can be considered as extensions of the already existing models for diffusion coupled phase transformations. We...
The coarsening kinetics of Cu-rich precipitates in an a-Fe matrix for thermally aged Fe-Cu alloys at temperatures above 700 °C is studied using a kinetic Monte Carlo (KMC) and a Phase-field method (PFM). In this work, KMC adequately captures the early stage of the systemevolutionwhich involves nucleation, growth and coarsening, while PFM provides t...
Eutectic growth is an interesting example for exploring the topic of pattern-formation
in multi-phase systems, where the growth of the phases is coupled with the diffusive transport
of one or more components in the melt. While in the case of binary alloys, the number of
possibilities are limited (lamellae, rods, labyrinth etc.), their number rap...
Eutectic growth offers a variety of examples for pattern formation which are interesting both for theoretecians as well as experimentallists. One such example of patterns are ternary eutectic colonies which arise as a result of instabilities during growth of two solid phases. Here, in addition to the two major components being exchanged between the...
Computational models based on the phase-field method typically operate on a mesoscopic length scale and resolve structural changes of the material and furthermore provide valuable information about microstructure and mechanical property relations. An accurate calculation of the stresses and mechanical energy at the transition region is therefore in...
In directional solidification of binary eutectics, it is often observed that two-phase lamellar growth patterns grow tilted with respect to the direction z of the imposed temperature gradient. This crystallographic effect depends on the orientation of the two crystal phases α and β with respect to z. Recently, an approximate theory was formulated t...
In this paper we derive an approach for the effective utilization of thermodynamic data in phase-field simulations. While the most widely used methodology for multi-component alloys is following the work by Eiken et al. (2006), wherein, an extrapolative scheme is utilized in conjunction with the TQ interface for deriving the driving force for phase...
We present a survey on different numerical interpolation schemes used for two-phase transient heat conduction problems in the context of interface capturing phase-field methods. Examples are general transport problems in the context of diffuse interface methods with a non-equal heat conductivity in normal and tangential directions to the interface....
We show simulation techniques that enable to computationally bridge from the atomistic up to the mesoscopic scale. To evaluate the efficiency, we use a phase-field method to simulate symmetric thermal dendrites and start the computation at an early stage of solidification related to nucleation. The early structures are taken from the molecular dyna...
The NiAl-gamma-gamma'-system is numerically modeled using a multi-phase-field approach near its peritectic. The free energies are approximated as second order polynomials of the concentration. The parameters of these functions are fitted using experimentally determined values for the peritectic equilibrium concentrations and the liquidus/solidus sl...
In this work the microstructure evolution for a two phase
Fe-Cu-Ni ternary alloy is studied in order to understand the
kinetic composition paths during coarsening of precipitates. We have
employed a quantitative phase-field model utilizing the CALPHAD database
to simulate the temporal evolution of a multi-particle system in a
two-dimensional domain...
Ternary eutectics develop a rich variety of microstructures depending on the solidification conditions. This article describes a new procedure to analyze the three-phase arrangement in metallographic sections following solidification; this method provides a clear definition of both the interphase spacing and the degree of ordering. Distance and ang...
We utilize a quantitative phase-field model to simulate three-phase eutectic growth and the oscillatory instabilities at large spacings. We analyze the effect of symmetry in the selection of the oscillatory mode for the case of directional solidification. Going further from our previous article (Choudhury A.
et al., Phys. Rev. E, 83 (2011) 051608),...
Phase-field modeling has spread to a variety of applications involving phase transformations. While the method has wide applicability, derivation of quantitative predictions requires deeper understanding of the coupling between the system and model parameters. The book highlights a novel phase-field model based on a grand-potential formalism allowi...
We investigate the lamellar growth of pearlite at the expense of austenite
during the eutectoid transformation in steel. To begin with, we extend the
Jackson-Hunt-type calculation (previously used to analyze eutectic
transformation) to eutectoid transformation by accounting for diffusion in all
the phases. Our principal finding is that the growth r...
In this paper, we study the effect of solutal Marangoni convection (SMC) on the microstructure evolution in a monotectic system, using the convective Cahn-Hilliard and Navier-Stokes equations with a capillary tensor contributed by the chemical concentration gradient. At first, we simulate the spontaneous motion of two distant droplets induced by SM...
The coarsening kinetics of Cu-rich precipitates in an α-Fe matrix for thermally aged Fe–Cu alloys at temperatures above 700 °C is studied using a kinetic Monte Carlo (KMC) simulation and a phase-field method (PFM). In this work, the KMC approach adequately captures the early stage of the system evolution which involves nucleation, growth and coarse...
We investigate the lamellar growth of pearlite at the expense of
austenite during the eutectoid transformation in steel. To begin with,
we extend the Jackson-Hunt-type calculation, done previously for
eutectic transformation, to eutectoid transformation by accounting for
diffusion in all the phases. Our principal finding, is that the growth
rates,...
In this work we analyze the fragmentation of αα(FCC)(FCC) dendrites in the Al–Cu alloy for different compositions. We use the phase field model for the simulation of 2D and 3D dendrite solidification and consequent melting and fragmentation studies. Our efforts lie in understanding the dependence of temperature and the history of temperature cyclin...
In this article, we present two models to simulate solidification morphologies in monotectic alloys. With the first model, we investigate the morphological evolution under the influence of spinodal decomposition. The model requires that a gradient energy contribution for the concentration field should be incorporated, in order to stabilize phase se...
Results of a cellular automaton model and a phase field model are compared for simulations of dendritic solidification of an Al–4wt%Cu alloy, two- and three-dimensionally at different undercoolings. For the 2D problem, quantitative comparison of steady state dendrite tip velocities with the Lipton Glicksman Kurz model reveals a closer agreement of...
In this paper, we describe the derivation of a model for the simulation of phase transformations in multicomponent real alloys starting from a grand-potential functional. We first point out the limitations of a phase-field model when evolution equations for the concentration and the phase-field variables are derived from a free energy functional. T...
We model the Fe-Sn system by using a higher order polynomial to describe the free energy of the liquid, and study three different aspects in morphological evolution in the monotectic alloy. Firstly, phase separation, in which case the liquid decomposes into two, is investigated inside of the spinodal decomposition region. Secondly, we study the cor...
We present our current work in the field of computational materials sci-ence with the phase-field method on the high performance cluster XC 4000 of the KIT (Karlsruhe Institute of Technology). Our investigations include heat conduction of open cell metal foams, dendritic growth and optimizations of the concurrent pro-cessing with the message passin...
A review surveying the developments in the application of the phase-field method in the study of phase transitions and microstructure evolution in multi-component systems is presented. Starting with a brief description of historical developments in the modelling method, we continue to take a tour into the applications of the method, both, in the un...
We investigate lamellar three-phase patterns that form during the directional solidification of ternary eutectic alloys in thin samples. A distinctive feature of this system is that many different geometric arrangements of the three phases are possible, contrary to the widely studied two-phase patterns in binary eutectics. Here, we first analyze th...
We use a thermodynamically consistent multi-phase, multi-component phase-field model, where the evolution equations for the different fields are derived from an entropy functional, for simulating peritectic growth structures in two and three dimensions. Different solidification morphologies are obtained in the computations and the characteristic pr...
In this paper an attempt has been made to arrive at a relation between the heat of formation of an intermetallic and the milling energy required for its formation during mechanical alloying. This has been demonstrated in case of B2 intermetallic compounds, namely, NiAl, FeAl, CoAl and MnAl. The milling energy corresponding to the start of formation...
Projects
Projects (5)
Phase-field modeling of micro-structure evolution during solid-state phase transformations particularly under the influence of coherency strains. Goals involve modeling of real materials, utilization of lower-length scale data relating to misfits and their dependency on composition, deriving information and comparing to atom-probe measurements of composition profiles across interfaces.
Understanding morphological evolution of eutectic micro-structures during directional solidification using numerical phase-field simulations and directional solidification experiments.
Understanding grain-growth and migration of interfaces under combined influence of electric current and thermal gradients
