Morphological transitions in the rapid solidification regime - A re-examination of the fundamental validity of the absolute stability concept of Mullins and Sekerka

The validity of the notion of absolute stability (AS) of a planar solid-liquid interface, proposed by Mullins and Sekerka (M-S, 1964), was tested using experimental data obtained for a number of dilute Ag-Cu and Sn-In alloys and for ultrahigh-purity succinonitrile. It is shown that the restriction applied by the M-S theory is satisfied during the steady-state planar solidification in an undercooled melt, provided the undercooling is quite small. The findings obtained on the Ag-Cu and Sn-In alloys are compared with early measurements by Davis and Fryzuk (1971) in dilute Sn-In alloys with 25 to 400 ppm additions of In.