Thermodynamic properties of α nickel--indium alloys

The vapor pressure of indium over α Ni--In alloys was measured by atomic absorption. The thermodynamic activity of indium was calculated from the vapor pressure, and the partial and integral entropy and enthalpy were calculated from temperature coefficients. It was found that the excess chemical potential of indium increases with atom fraction of indium at low temperatures, in the manner generally observed with similar alloys, but that the slope changes sign, causing Δ anti G/sub In//sup xs/ to decrease with increasing x/sub In/ at high temperatures. An analysis of the components of the excess entropy indicated that the excess entropy, which has a large negative value, has a major contribution which can be attributed to the conduction electrons. Such an electronic contribution to ΔS/sup xs/ is in accord with the band structure thought to characterize nickel-base alloys