To cite this version:S Bottin-Rousseau, M S erefoglu, Sinan Yücetürk, Gabriel Faivre, Silvère Akamatsu. Stability of three-phase ternary-eutectic growth patterns in thin sample. Acta Materialia, Elsevier, 2016, 109, pp.259 -266. <10.1016/j.actamat.2016 Abstract Near-eutectic ternary alloys subjected to thin-sample directional solidification can exhibit stationary periodic growth patterns with an ABAC repeat unit, where A, B and C are the three solid phases in equilibrium with the liquid at the eutectic point. We present an in-situ experimental study of the dynamical features of such patterns in a near-eutectic In-In 2 Bi-Sn alloy. We demonstrate that ABAC patterns have a wide stability range of spacing at given growth rate. We study quantitatively the -di↵usion process that is responsible for the spacing uniformity of steady-state patterns inside the stability interval. The instability processes that determine the limits of this interval are examined. Qualitatively, we show that ternary-eutectic ABAC patterns essentially have the same dynamical features as two-phase binary-eutectic patterns. However, lamella elimination (low-stability limit) occurs before any Eckhaus instability manifests itself. We also report observations of stationary patterns with an [AB] m [AC] n superstructure, where m and n are integers larger than unity.Keywords: Eutectic solidification, directional solidification, solidification microstructures, ternary eutectics, three phase microstructures. IntroductionThe solidification microstructures of ternary eutectic alloys take many di↵er-ent forms depending on the composition and grain structure of the alloy, the geometrical and thermal features of the solidification device, and the solidification history. The most important of these factors are the number of growing phases and the dimensionality of the samples. We are concerned here with two-dimensional three-phase microstructures. These are typically observed in near-eutectic ternary alloys subjected to thin-sample directional solidification (thin-DS). Solidification microstructures are, we recall, nothing else than the trace left behind in the solid by out-of-equilibrium self-organized patterns formed during solidification. At constant solidification rate V and applied thermal gradient G, these patterns generally reach, or, at least, asymptotically tend towards a steady-state. The most wellknown example of a steady-state eutectic growth pattern is the periodic (lamellar) two-phase solidification pattern of near-eutectic binary alloys analyzed by Jackson and Hunt (JH) a long time ago [1]. The repeat unit of such a pattern is an AB pair of lamellae, where A and B are the two solid phases in equilibrium with the liquid at the eutectic point. These AB patterns have mirror symmetry with respect to the mid-plane of the lamellae, which is actually a condition for their steadiness. Regarding ternary eutectic alloys, the basic repeat unit of stationary thin-DS patterns is ABAC, where A, B and C are the three eutectic solid phases. It has mirror sy...