Characterization of hypereutectic Al-Si powders solidified under far-from equilibrium conditions


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Kalay Y. E. , CHUMBLEY L. S. , ANDERSON I. E. , NAPOLITANO R. E.

METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, no.7, pp.1452-1457, 2007 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Publication Date: 2007
  • Doi Number: 10.1007/s11661-007-9168-8
  • Title of Journal : METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
  • Page Numbers: pp.1452-1457

Abstract

The rapid solidification microstructure of gas-atomized Al-Si powders of 15, 18, 25, and 50 wt pet Si were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In order of increasing particle size, the powders exhibited microcellular Al, cellular/dendritic Al, eutectic Al, and primary Si growth morphologies. Interface velocity and undercooling were estimated from measured eutectic spacing based on the Trivedi-Magnin-Kurz (TMK) model, permitting a direct comparison with theoretical predictions of solidification morphology. Based on our observations, additional conditions for high-undercooling morphological transitions are proposed as an extension of coupled-zone predictions.