Dynamic effects in the lamellar-rod eutectic transition

TitleDynamic effects in the lamellar-rod eutectic transition
Publication TypeJournal Article
Year of Publication2011
AuthorsLiu S, Lee JH, Trivedi R
Journal TitleActa Materialia
Volume59
Pages3102-3115
Date Published05
Type of ArticleArticle
ISBN Number1359-6454
Accession NumberISI:000290053100020
Keywordsaluminum alloys, diffusion, directional solidification, eutectic solidification, interface dynamics, Lamellar-rod transition, stability, systems
Abstract

Critical experiments in the Al-Cu system are carried out to establish the conditions for the stability of rod and lamellar eutectics. It is shown that the instability of a lamella initiates locally through the formation of a sinusoidal perturbation, and the fastest growing wavelength of perturbation, which corresponds to the rod spacing, is related to the local lamella spacing. The instabilities in adjacent lamellae are observed to be out of phase to give rise to a hexagonal arrangement of rods at the transition. The specific relationship found between the unstable lamella spacing and the resulting rod spacing at the transition is then taken into account to develop a general model of the rod lamellar transition which also includes the relative undercooling and the presence of a spacing distribution. A microstructure map is presented which defines the regimes of rod, lamellar and mixed structures, which is shown to be in good agreement with the experimental results. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

URL<Go to ISI>://000290053100020
DOI10.1016/j.actamat.2011.01.050
Alternate JournalActa Mater.