Decoupled versus coupled growth dynamics of an irregular eutectic alloy


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Mohagheghi S., Bottin-Rousseau S., Akamatsu S., Serefoglu M.

SCRIPTA MATERIALIA, vol.189, pp.11-15, 2020 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 189
  • Publication Date: 2020
  • Doi Number: 10.1016/j.scriptamat.2020.07.053
  • Title of Journal : SCRIPTA MATERIALIA
  • Page Numbers: pp.11-15
  • Keywords: Irregular eutectic growth, Directional solidification, Eutectic solidification, Interface dynamics, Solidification microstructures, SOLIDIFICATION, SILICON, LAMELLAR

Abstract

We present an experimental study of irregular growth patterns observed in real time during thinsample directional solidification of a faceted/nonfaceted eutectic alloy, namely, the transparent 2-amino-2-methyl-1,3-propanediol (AMPD)-succinonitrile (SCN) system. The body-centered cubic SCN crystals are nonfaceted, while monoclinic AMPD crystals grow as faceted needles. At low velocities (<0.3 mu ms(-1)), a decoupled growth regime is observed, during which the tip of the AMPD crystals grows ahead of the SCN-liquid interface. At intermediate velocities, an unsteady coupled-growth regime takes place, with intermittent pinning of triple SCN-AMPD-liquid junctions, and frequent noncrystallographic branching. At higher velocities (>1 mu ms(-1)), two-phase fingers form. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.