AN INVESTIGATION OF THE THERMODYNAMIC PROPERTIES OF SOME LIQUID TIN ALLOYS.
Final technical rept.,
DENVER RESEARCH INST COLO
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The heats of solution of various elements in liquid tin have been investigated as a function of both temperature and composition. The elements studied included palladium, tellurium, rhodium, lithium, calcium, barium, strontium and lanthanum. The temperature range involved was from 700 K to 775 K and compositions from zero to 10 atomic percent solute were investigated. Heats of formation of several intermediate solid phases in the palladium-tin, tellurium-tin, rhodium-tin and lanthanum-tin systems have also been determined. Liquid densities of pure tin and palladium-tin alloys have been measured as a function of temperature and alloy composition. In all alloy systems the partial molar heat of solution of the solute in liquid tin is large and negative, ranging from a minimum value of -7600 caloriesg-atom for tellurium at 775 K to a maximum value of -67,000 caloriesg-atom for lanthanum at 725 K. The values for the other solutes involved are in the range -25,000 caloriesg-atom to -42,000 caloriesg-atom. This highly exothermic heat of solution indicates a high degree of association between solute atoms and solvent atoms in the liquid state. This conclusion is supported by both the heat of formation measurements and the density measurements. The heats of formation of the intermediate phases in the palladium-tin system are slightly more exothermic than the heat of solution of palladium in liquid tin. This difference can be attributed to the energy necessary to melt the solid intermediate phase, thus forming molecular type liquid. Density measurements on the palladium-tin system also indicate a high degree of solute-solvent bonding in the liquid state. Author
- Properties of Metals and Alloys