Stability of three-phase ternary-eutectic growth patterns in thin sample


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Bottin-Rousseau S., ŞEREFOĞLU KAYA M. , Yuceturk S., Faivre G., Akamatsu S.

ACTA MATERIALIA, vol.109, pp.259-266, 2016 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 109
  • Publication Date: 2016
  • Doi Number: 10.1016/j.actamat.2016.01.065
  • Title of Journal : ACTA MATERIALIA
  • Page Numbers: pp.259-266
  • Keywords: Eutectic solidification, Directional solidification, Solidification microstructures, Ternary eutectics, Three phase microstructures, IN-SITU OBSERVATION, SN SYSTEM, LAMELLAR, SOLIDIFICATION, ALLOYS, MICROSTRUCTURE, ANISOTROPY

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-In2Bi-Sn alloy. We demonstrate that ABAC patterns have a wide stability range of spacing lambda at given growth rate. We study quantitatively the lambda-diffusion 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-lambda 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. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.