Mechanisms of eutectic solidification in Al-Si alloys modified with Ba, Ca, Y and Yb

Kazuhiro Nogita, A. Knuutinen, S. D. McDonald, A. K. Dahle

Research output: Contribution to journalArticle

65 Citations (Scopus)

Abstract

The eutectic solidification mechanisms in an A356.0 (Al-7%Si-Mg) alloy modified by barium, calcium, yttrium and ytterbium have been determined. The crystallographic orientations of aluminium in the eutectic and the surrounding aluminium dendrites were measured by electron backscattering diffraction mapping, and samples were also quenched at different stages during the eutectic arrest and examined by optical microscopy. The combination of these two techniques shows that each of the elements added promote heterogeneous nucleation of eutectic grains in the interdendritic liquid, while the aluminium in the unmodified alloy grows epitaxially from the dendrites. Furthermore, calcium and yttrium result in a strong dependency of eutectic solidification on the thermal gradient, i.e. the eutectic evolves from the walls towards the centre of the sample on a macro-scale. These differences in eutectic solidification mode show a correlation with some thermal characteristics of the eutectic arrest.

Original languageEnglish
Pages (from-to)219-228
Number of pages10
JournalJournal of Light Metals
Volume1
Issue number4
DOIs
Publication statusPublished - Nov 1 2001

    Fingerprint

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

Cite this