Sr-Al-Si co-segregated regions in eutectic Si phase of Sr-modified Al-10Si alloy

M. Timpel, N. Wanderka, R. Schlesiger, T. Yamamoto, D. Isheim, G. Schmitz, S. Matsumura, J. Banhart

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

The addition of 200. ppm strontium to an Al-10. wt% Si casting alloy changes the morphology of the eutectic silicon phase from coarse plate-like to fine fibrous networks. In order to clarify this modification mechanism the location of Sr within the eutectic Si phase has been investigated by a combination of high-resolution methods. Whereas three-dimensional atom probe tomography allows us to visualise the distribution of Sr on the atomic scale and to analyse its local enrichment, transmission electron microscopy yields information about the crystallographic nature of segregated regions. Segregations with two kinds of morphologies were found at the intersections of Si twin lamellae: Sr-Al-Si co-segregations of rod-like morphology and Al-rich regions of spherical morphology. Both are responsible for the formation of a high density of multiple twins and promote the anisotropic growth of the eutectic Si phase in specific crystallographic directions during solidification. The experimental findings are related to the previously postulated mechanism of "impurity induced twinning".

Original languageEnglish
Pages (from-to)216-221
Number of pages6
JournalUltramicroscopy
Volume132
DOIs
Publication statusPublished - Sep 2013

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Instrumentation

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