Viscosity of molten Pd40Ni40P20

Abstract

The viscosity of molten Pd₄₀Ni₄₀P₂₀ was measured from 980 to 1160 K by capillary flow method. At temperatures below its liquidus ∼1030 K, the measurement was carried out with the molten specimen immersed in anhydrous boron oxide flux in order to inhibit the formation of small crystallites. In the presence of crystallites, the viscosity values were scattered and also were considerably larger than those of crystallite free liquid. The viscosity of crystallite free molten Pd₄₀Ni₄₀P₂₀ can be described by the following Vogel–Fulcher equation: ln η=−4.072+1310.1/(T−551). The curve here cannot be joined to those viscosity data of Volkert and Spaepen [Mater. Sci. and Eng. 97, 449 (1988)] of the same system near the glass transition temperature by a single Vogel–Fulcher equation of constant parameters. Earlier, Polk and Turnbull [D. E. Polk and D. Turnbull, Acta Metall. 20, 493 (1972)] determined the viscosity of molten Au₇₇Ge_13.6Si_9.4 also by the capillary method. Their results were compared with the current work and it was found that the principle of corresponding states apparently holds here and the reduced temperature is defined as T/T_g.