SOLIDIFICATION AND MICROSTRUCTURE ANALYSIS OF RAPIDLY SOLIDIFIED MELT-SPUN AL-FE ALLOYS

Aluminum-iron alloys with Fe contents of up to 8 wt pct were rapidly quenched from the melt using the planar-flow melt-spinning technique. Microstructural changes that occur across the thickness of melt-spun ribbons were investigated as a function of initial melt composition and ribbon thickness. A transition exhibiting a dramatic change in the cell spacing from a microcellular to a coarse cellular region was observed for all the alloys examined. For a given alloy, the volume fraction of the microcellular region decreases significantly with increasing ribbon thickness. A theoretical explanation for the observed behavior is presented in which the heat flow and solidification characteristics are related to the undercooling achieved before the onset of nucleation. © 1990 The Metallurgical of Society of AIME.