The rapid solidification microstructure of gas-atomized Al-Si powders of 15, 18, 25, and 50 wt pct 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.
Copyright 2007 ASM International. This paper was published in Metallurgical and Materials Transactions A, Vol. 38, Issue 7, pp. 1452-1457 and is made available as an electronic reprint with the permission of ASM International. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplications of any material in this paper for a fee or for commercial purposes, or modification of the content of
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Y. E. Kalay, L. Scott Chumbley, Iver E. Anderson and Ralph E. Napolitano. "Characterization of Hypereutectic Al-Si Powders Solidified under Far-From Equilibrium Conditions" Metallurgical and Materials Transactions A
Vol. 38 Iss. 7 (2007) p. 1452 - 1457
Available at: http://works.bepress.com/ralph_napolitano/5/