An investigation of the density and the surface tension in liquid Ag-Bi-Sn alloys

The density and surface tension of liquid alloys of the ternary system Ag-Bi-Sn were measured by a sessile drop method at temperatures up to 1,000 K. The investigation concentrated on sections of constant Ag/Bi composition ratios. Both quantities show a linear decrease with the temperature. The experimental surface tensions are in acceptable agreement with the calculations based on the thermodynamic activities of the components in the system. Over a wide range of composition the surface tension is not dramatically increased by the presence of Ag in the alloys which results presumably from the preferential occupancy of the surface layer by atoms of Bi and Sn. The non-simple variation of the densities with the composition points to a reduction in volume due to the mixing process which is discussed with particular regard to the literature data on the binary system Ag-Bi. The volume effects are indicated to occur predominantly near the Ag corner of the ternary system.