AN INDICATION OF PREDECOMPOSITION PHENOMENON OF LIQUID AL-IN ALLOYS ABOVE THE BINODAL TEMPERATURE FOUND BY VISCOSITY INVESTIGATIONS

Using an oscillating crucible viscosimeter the viscosities of liquid A lxIn100-x alloys have been measure (x = 100, 80, 70, 60, 50, 40 at.%) in the temperature range from 1470 K to the binodal temperature of the alloys or the solidification temperature of pure aluminium respective ly. The binodal curve is the T-x line that is the locus of points dete rmined by the same chemical potential of the components in the conjuga ted phases. The experiments permit one to determine the binodal curve using the existence of a significant peak of the viscosity plotted ver sus the temperature. The deviations of the viscosity from the Arrheniu s plot in a certain temperature range above the decomposition temperat ure support the view of predecomposition on a microscopic scale. The v olume part of atoms involved will be estimated. The temperature depend ence of the viscosity near the critical point will be described with c ritical exponents.