ON THE PARTIAL ATOMIC VOLUME AND THE PARTIAL MOLAR ENTHALPY OF ALUMINUM IN SOME PHASES WITH CU AND CU3AU STRUCTURES

The lattice parameters and macroscopic densities of the solid solutions of Co(Al), Rh(Al), Ir(Al), Ni(Al), Cu(Al), Ag(Al) and Au(Al) and the intermetallic compounds of Ni3AI and Ag2Al were measured over the whole range of homogeneity. The dependence of both the average atomic volume and the enthalpy of formation on mole fraction was investigated for the systems A9-Al (A9 = Co, Rh, Ir), A1O-Al (A10 = Ni, Pd, Pt) and B11-Al (B11 = Cu, Ag, Au). The partial atomic volume and the partial molar enthalpy of aluminium were analysed for phases with the Cu and CU3Au structures. Among the quasi-homological systems, the smallest values for the partial atomic volume of aluminium and the most negative values for the partial molar enthalpy of aluminium were found in the solid solutions A10' (Al). These indicate a strong charge transfer from aluminium-atoms to atoms of nickel, palladium and platinum.