Two liquid phase separations of liquid Bi-Ga alloys under low gravity

Abstract

Electrical resistance, R, of liquid Bi-Ga alloys was investigated on cooling both on earth and under low gravity; the latter case was realized by the launch of an S520 rocket belonging to ISAS. The temperature dependence of R, dR/dT, of the homogeneous liquid phase increases on cooling from 573K to the coexistence curve (Binodal line) temperature T L (539K). Below T L , the increasing tendency of dR/dT becomes steep down to the onset temperature, T s , of two liquid phase separation. These tendencies were far more distinct for an experiment under low gravity than one on earth. For example, a distinct increase of dR/dT begins at T L +15 K for the rocket experiment of liquid Bi-65at.% Ga alloy. On the other hand a slight increase of dR/dT continues gradually up to T s for an experiment on earth. Moreover, the degree of supercooling, T L - T s , is far larger under low gravity condition than 1 G (on earth) condition. These differences are explained by the difference of convection effects among fluctuating domains. It is concluded that the low gravity condition is essential to clarify the substantial feature of critical phenomena, supercooling behaviour, phase separation process and Spinodal process in liquids with critical mixing.