Viscosity of liquid In–Se–Tl alloys in the miscibility gap region

The shear viscosity measurements were performed for liquid InxSe20Tl80−x (0 ≤ x ≤ 80 at.%) alloys over a wide temperature range above the monotectic using an oscillating-cup viscometer. In this range the ternary In–Se–Tl system may be considered as a set of “quasibinary” immiscible metal-chalcogen alloys of critical composition. Variation of the In/Tl ratio at a constant Se content changes the properties of the coexisting liquids and affects the temperature of demixing. The critical parameters describing the peculiarities of the viscosity behavior in the vicinity of the critical point are evaluated. Based on the dynamic theory of phase transitions a description of the viscosity in the region of phase separation is proposed. The results are compared with available data for immiscible dielectric solutions and metallic melts.