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Self-organized Sr leads to solid state twinning in nano-scaled eutectic Si phase.

ABSTRACT: A new mechanism for twin nucleation in the eutectic Al-Si alloy with trace Sr impurities is proposed. Observations made by sub-angstrom resolution scanning transmission electron microscopy and X-ray probing proved the presence of <110> Sr columns located preferentially at twin boundaries. Density functional theory simulations indicate that Sr atoms bind in the Si lattice only along the <110> direction, with preferential positions at first and second nearest neighbors for interstitial and substitutional Sr, respectively. Density functional theory total energy calculations confirm that twin nucleation at Sr columns is energetically favorable. Hence, twins may nucleate in Si precipitates after solidification, which provides a different perspective to the currently accepted mechanism which suggests twin formation during precipitate growth.

SUBMITTER: Albu M

PROVIDER: S-EPMC4985832 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature

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Self-organized Sr leads to solid state twinning in nano-scaled eutectic Si phase.

Albu M M Pal A A Gspan C C Picu R C RC Hofer F F Kothleitner G G

Scientific reports 20160816

A new mechanism for twin nucleation in the eutectic Al-Si alloy with trace Sr impurities is proposed. Observations made by sub-angstrom resolution scanning transmission electron microscopy and X-ray probing proved the presence of <110> Sr columns located preferentially at twin boundaries. Density functional theory simulations indicate that Sr atoms bind in the Si lattice only along the <110> direction, with preferential positions at first and second nearest neighbors for interstitial and substit ...[more]

PMID: 27527789

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