COMPOSITION AND SOLIDIFICATION MICROSTRUCTURE SELECTION IN THE INTERDENDRITIC MATRIX BETWEEN PRIMARY Al_3Fe DENDRITES IN HYPEREUTECTIC Al-Fe ALLOYS

摘要

The composition and constitution of matrix microstructure between plate-like Al_3 Fe dendrites in Bridgman-grown hypereutectic Al-Fe alloys has been determined as a function of alloy concentration C_0 and growth velocity V in the ranges 2.5 < C_0 < 28.1 wt/100Fe and 0.01 < V < 5.0 mm/s. The transition at V=0.1 mm/s from a fully eutectic matrix at C_0= 3.5wt/100 Fe to one containing αAl dendrites at C_0≥ 4.7 wt/100 Fe is attributed to growth temperatures of αA1 dendrites that are higher than those of eutectic in a matrix of lower iron-content, which results from these conditions.