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 energy anisotropy. In this paper, we provide evidence using phase-field simulations where our focus is on alloys where the minority phase fraction is low. Our aim is to establish the role of solid-solid interfacial energy anisotropy in the stabilization of broken lamellar structures in such systems in contrast to the formation of a rod microstructure. In this regard, we conduct phase-field simulations for different strengths of anisotropy in both constrained and extended settings, using which we clarify the mechanisms by which a lamellar arrangement gets stabilized in the presence of anisotropy in the solid-solid interfacial energy.

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 expected hexagonal arrangement of Zn rods in the Sn matrix. Thus, the main objective of the study is to investigate the reasons behind this phenomenon. We begin by presenting experimental results detailing the morphology and crystallography of the eutectic microstructures under various combinations of thermal gradients and velocities in directional solidification conditions. Based on the crystallography and further specially designed experiments we find that the solid-solid interface between the Sn and Zn crystal is anisotropic. On the basis of the results, we propose a hypothesis that the presence of solid-solid interfacial energy anisotropy leads to the formation of predominantly broken-lamellar structures, even when the minority fraction is significantly low.

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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 efficiencies, is non-trivial as the parameter space is large and a theoretical framework is necessary. This is specifically important for determining the appropriate compositions of the ternary blend which, upon phase-separation, lead to the formation of the heterogenous active layer with a distribution of three phases. In this paper, we present an approach for deriving both the process–structure and structure–property correlations based on the diffuse-interface approach. Herein, we derive process–structure correlations using phase-field simulations based on the Cahn–Hilliard formalism for modeling phase-separation in ternary systems where a third component that acts as an acceptor is added to a binary OPV. This leads to structures that can be classified as donor–acceptor–acceptor. Thereafter, we derive the structure–property correlations again using a diffuse interface approach for deriving the electronic properties such as the efficiency, fill-factor, short-circuit current, and the open-circuit voltages for the simulated microstructures involving the three phases in the active layer. Thus, using a combination of the process–structure and structure–property correlations, optimal compositions can be determined. Further, in order to expedite the theoretical prediction, a robust and elegant data analytics model is built using dimensionality reduction techniques.