The role of strontium in modifying aluminium-silicon alloys

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

研究成果: Contribution to journalArticle査読

214 被引用数 (Scopus)

抄録

Small amounts of strontium can transform the morphology of the eutectic silicon phase present in Al-Si casting alloys from coarse plate-like to fine fibrous networks. In order to understand this industrially important but hitherto insufficiently understood effect, the strontium distribution was studied in atomic resolution by atom probe tomography and in nanometre resolution by transmission electron microscopy. The combined investigations indicate that Sr co-segregates with Al and Si within the eutectic Si phase. Two types of segregations were found: (i) nanometre-thin rod-like co-segregations of type I are responsible for the formation of multiple twins in a Si crystal and enable its growth in different crystallographic directions; (ii) type II segregations come as more extended structures, restrict growth of a Si crystal and control its branching. We show how Sr enables both kinds of mechanisms previously postulated in the literature, namely "impurity-induced twinning" (via type I) and growth restriction of eutectic Si phase (via type II).

本文言語英語
ページ(範囲)3920-3928
ページ数9
ジャーナルActa Materialia
60
9
DOI
出版ステータス出版済み - 5 2012

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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