arXiv subjects

T. A. Abinandanan

Publications and source records attributed to T. A. Abinandanan.

5 recordsLinked to original sources

arXiv2026

Size focusing in core-shell precipitates: A phase-field study

Due to their enhanced resistance to coarsening and/or creep, aluminium alloys with precipitates of two distinct phases in a core-shell morphology are of great contemporary interest. In this paper, we focus on the curious observation in two recent studies on Al-Sc-Li and Al-Yb-Li alloys that growth of the shell phase leads to a narrowing of the size distribution. We have studied this phenomenon, known as size focusing, using a theoretical framework (which extends Zener's theory of diffusional growth to a core-shell precipitate) and multi-precipitate simulations based on a phase field model. Our results yield key theoretical insights as well as conclusions with practical significance. (a) On the theoretical front, we show clearly that size focusing is a growth phenomenon: it ends when shell growth ends, and coarsening begins. (b) On the practical front, our results offer guidelines for designing alloys with narrower size distributions: size focusing is promoted in alloys with greater shell volume fractions and greater inter-precipitate spacing.

cond-mat.mtrl-sci↗

arXiv2026

Bridging Phase-Field Model and Deep Learning for Predicting 2D and 3D Microstructure Evolution in Ternary Alloys

We develop a hybrid framework that integrates a phase-field model (PFM) with an attention-enhanced deep learning (DL) architecture to study ternary spinodal dealloying, a sophisticated self-organization approach used to fabricate three-dimensional bicontinuous, hierarchical nanoporous materials. The study captures three distinct phase-separation mechanisms that emerge during the early stages of spinodal decomposition in both two and three dimensions. The DL workflow consists of three key components: (i) a dimensionality-reducing autoencoder that provides compact representations of high-resolution microstructure images (256x256x3), (ii) an attention-augmented convolutional long short-term memory (ConvLSTM) network that learns complex spatiotemporal correlations governing microstructure evolution, and (iii) a novel slice-by-slice strategy that enables extension of the model to three-dimensional systems (128x128x128x3). We further demonstrate a hybrid simulation strategy in which PFM accurately captures rapid early-stage microstructure evolution, while the DL model efficiently predicts late-stage coarsening dynamics. The trained DL model achieves remarkable predictive accuracy, maintaining fidelity up to 400 timesteps ahead and generalizing to compositions outside the training distribution. By bridging the physical fidelity of PFM with the computational efficiency of DL, this framework establishes a robust platform for predictive modeling of microstructure evolution in complex multicomponent systems.

cond-mat.mtrl-sci↗

arXiv2017

Particles with selective wetting affect spinodal decomposition microstructures

We have used mesoscale simulations to study the effect of immobile particles on microstructure formation during spinodal decomposition in ternary mixtures such as polymer blends. Specifically, we have explored a regime of interparticle spacings (which are a few times the characteristic spinodal length scale) in which we might expect interesting new effects arising from interactions among wetting, spinodal decomposition and coarsening. In this paper, we report three new effects for systems in which the particle phase has a strong preference for being wetted by one of the components (say, A). In the presence of particles, microstructures are not bicontinuous in a symmetric mixture. An asymmetric mixture, on the other hand, first forms a non-bicontinuous microstructure which then evolves into a bicontinuous one at intermediate times. Moreover, while wetting of the particle phase by the preferred component (A) creates alternating A-rich and B-rich layers around the particles, curvature-driven coarsening leads to shrinking and disappearance of the first A-rich layer, leaving a layer of the non-preferred component in contact with the particle. At late simulation times, domains of the matrix components coarsen following the Lifshitz-Slyozov-Wagner law, $R_1(t) \sim t^{1/3}$.

cond-mat.mtrl-sci↗

arXiv2016

Growth in multi-component alloys: Theoretical and numerical determination of phase concentrations

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 profiles in the matrix during growth of planar and cylindrical precipitates with the assumption of diagonal diffusivity matrices. We confirm our calculations by sharp interface and phase field simulations. The numerical techniques are in turn utilized for investigating the role of off-diagonal entries in the diffusivity matrix. In addition, the sharp interface methods allow for the tracking of the tie-line compositions during growth of 2D precipitates which contribute to an understanding of the change in equilibrium tie-lines chosen by the system during growth.

cond-mat.mtrl-sci↗

arXiv2013

Effect of Epitaxial Strain on Phase Separation in Thin Films

We examine the role of an imposed epitaxial strain e in enhancing or depressing the spinodal instability of an alloy thin film. Since the alloy film starts with an imposed strain, phase separation offers a mechanism to relieve it, but only when the film is elastically inhomogeneous. With composition-dependence of elastic modulus given by y, and that of lattice parameter by η, our simulations using the Cahn-Hilliard model show (and analytical results for early stages confirm) that, for (ey/η) > 0, the imposed strain adds to the driving force for phase separation, decreases the maximally growing wave length, and expands the coherent spinodal in the phase diagram. Further, when (ey/η) > 0.372, it expands to even outside of chemical spinodal. Phase separation produces islands of elastically softer (harder) phase with (without) a favorable imposed strain. These results are in agreement with experimental results in GeSi thin films on Si and Ge substrates, as well as in InGaAs films on GaAs substrates.

cond-mat.mtrl-sci↗