Nondirectional solidification experiments involving several hypermonotectic Cu-Pb-Al alloys were carried out aboard NASA's KC-135 zero-g aircraft in order to determine the influence of interfacial energies and gravity levels on dispersion-forming tendencies. For Cu-Pb-Al alloys, changes in Al content are thought to result in variations in the interfacial energy between the two liquid phases. It has been postulated that the interfacial energy between the two liquid phases may have a strong influence on the ability to form well-dispersed structures in these systems. In order to study the influence of interfacial energies, the Al content was systematically varied in the alloys. To eliminate gravity driven sedimentation of the more dense immiscible liquid phase during solidification, experimentation was carried out aboard NASA's KC-135 zero-g aircraft. The resulting structures have been analyzed and the dispersion-forming ability related to the gravity level during solidification, the interfacial energy between the immiscible phases, and the tendency for the minority immiscible phase to wet the walls of the crucible. © 1988 The Metallurgical of Society of AIME.