Investigations of the Viscosity of the Ternary Co81(B,Si)19 and Co75(B,Si)25 Melts

Abstract

The temperature (polytherms) and concentration (isotherms) dependences of the kinematic viscosity of melts of the ternary Co 81 (B,Si) 19 and Co 75 (B,Si) 25 systems have been experimentally studied. The polytherms of liquid alloys obtained in the heating and cooling regimes coincide and are well described by the exponential Arrhenius equation. The concentration dependences of the viscosity of ternary systems for the quasi-binary Co 81 B 19 -Co 81 Si 19 and Co 75 B 25 -Co 75 Si 25 sections at fixed temperatures were plotted using polytherms. For both systems, the extreme points on the viscosity isotherms corresponding to binary alloys have similar values at the same temperatures. The viscosity isotherms of the quasi-binary sections are close to the additive sum of the viscosity values of binary alloys with a small positive deviation. When the temperature of the melt changes the character of the viscosity isotherms does not change significantly. The calculations of the concentration dependences of the dynamic viscosity of the melts of the Сo 81 B 19 -Co 81 Si 19 and Сo 75 B 25 -Co 75 Si 25 systems were carried out according to the equations based on the data on the thermodynamic properties of the melt and/or the physical properties of its components. The calculations were carried out according to the following equations: Kozlov-Romanov-Petrov; Kaptay; Chhabra; Sato; Hirai; Budai-Benkö-Kaptay and Živković-(Budai-Benkö-Kaptay). For both ternary systems, the best agreement with the experimental data is shown by the Kozlov-Romanov-Petrov equation both in the nature of the isotherm and in the viscosity values. The maximum relative deviation of the viscosity isotherm calculated by the Kozlov-Romanov-Petrov equation from the isotherm obtained in the experiment does not exceed 15 %.