On the Excess Viscosity of Liquid Alloys and the Atomic Interaction of Their Constituents

Abstract

An expression describing the excess viscosity of liquid binary alloys has been derived by use of some basic physical quantities, in order to estimate the viscosities of liquid alloys which are considered to be one of the most important properties in metallurgical processes, as follows;Δη= (x1η1+x2η2) [-5x1x2 (σ1-σ2) 2/x1σ21+x2σ22+2 {√1+ (x1x2√m1-√m2) 2/ (x1√m1+x2√m2) 2-1} -0.12x1x2Δu/kT]where, Δη: excess viscosity (cP), x: atomic fraction (x1+x2=1), η: viscosity of pure liquid metal, σ: diameter of the sphere (ionic radius after Pauling), m: atomic mass (m= M/NO, M: atomic weight, N0: Avogadro number), Δu: interchange energy (ΔH=x1x2NOΔu, ΔH: integral enthalpy of mixing), k: Boltzmann constant, T: absolute temperature. And the subscripts 1 and 2 refer to the components.In the square bracket of the above equation, the first and the second terms show hard part and the third term represents soft part of friction constant for viscous movements.Values calculated from the above equation for the excess viscosity of various liquid binary alloys coincided qualitatively with their experimental data, and in particular, for regular or nearly regular solutions, an excellent agreement has been found between those calculated and experimentally observed.