THE LIMITING MOLAR PARTIAL ENTHALPIES OF MIXING OF IRON, COBALT, NICKEL, PALLADIUM AND PLATINUM IN LIQUID GALLIUM AND INDIUM

Gallium and indium have been used as solvents for the determination of the molar partial enthalpy of mixing Delta(mix)h(m) degrees(TM, Ga or In) (denoting liquid transition metal (TM) in infinite liquid gallium or indium) of the pure liquid transition metals Fe, Co, Ni, Pd and Pt by direct reaction calorimetry between 1000 K and 1500 K with the exc eption of Delta(mix)h(m) degrees(Fe, In) (because of the shape of its equilibrium phase diagram). All the limiting enthalpies listed below r efer to the liquid state. With pure gallium as solvent, they correspon d to the reaction TM(liq) + nGa(liq) --> TM(1)Ga(n)(liq) at the experi mental temperature T-e, with n much greater than 1. (i) Delta(mix)h(m) degrees in gallium is found for Fe, Co, Ni, Pd and Pt to be -2, -44, -82, -144 and -155 kJ mol(-1). (ii) Delta(mix)h(m) degrees in indium i s found for Co, Ni, Pd and Pt to be +28, -25, -127 and -114 kJ mol(-1) . In both solvents, these limiting enthalpies vary with a similar tren d. This observation makes it possible to predict the limiting molar pa rtial enthalpy Delta(mix)h(m) degrees(Fe, In) of mixing of iron in ind ium as +70 kJ mol(-1). The results have been compared with the data pr oposed by Miedema and co-workers.