Thermochemistry of some binary alloys of noble metals (Cu, Ag, Au) and transition metals by high temperature direct synthesis calorimetry

The standard enthalpies of formation of some noble metal-transition metal compounds have been measured by high temperature direct synthesis calorimetry at 1372 K. The following results (in kJ/mol of atoms) are reported; Cu51Zr14, -24.3+/-2.2; Cu3Pd, -7.6+/-1.2; Cu51Hf14, -22.9+/-2.3; Cu3Pt, -10.8+/-1.1; AgTi, -1.6+/-2.4; AgTi2, -2.3+/-1.1; Ag2Y, -26.6+/-1.2; Au2Sc, -83.4+/-1.8; Au4Sc, -57.3+/-1.5; AuMn, -25.3+/-1.7; Au2Y, - 84.6+/-1.8; Au3Y, Pd, -69.1+/-1.9; Au3Pd, -7.9+/-1.9. The results are compared with some earlier experimental values obtained by EMF, by vapor pressure and by calorimetry. They are also compared with the predicted values of Miedema and coworkers. We will present a systematic picture of how the enthalpies of formation may be related to the atomic number of the transition metal. (C) 2002 Elsevier Science B.V. All rights reserved.