The standard enthalpies of formation of binary intermetallic compounds of some late 4d and 5d transition metals by high temperature direct synthesis calorimetry

Abstract

The standard enthalpies of formation of intermetallic compounds of some late 4d and 5d transition metals have been measured by high temperature, direct synthesis calorimetry at 1373 ± 2 K. The following results in kJ/mol of atoms are reported: NbMn2 (−10.4 ± 2.7); NbRu (−0.7 ± 2.8); RhMo (−4.8 ± 1.8); PdMn (−45.2 ± 2.2); Pd2Mo (−9.2 ± 1.9); TaMn2 (−14.5 ± 2.5); IrMn3 (−13.2 ± 2.8); Pt3Cr (−8.8 ± 3.1); PtMn (−53.6 ± 1.5); PtMo (−17.9 ± 2.2); Pt3Ta (−21.1 ± 2.4); and YMn2 (−2.8 ± 2.8). The values are compared with predicted values of Miedema and co-workers and with new results from ab initio calculations when available. We will present a systematic picture of how the enthalpies of formation may be related to the atomic number of the transition metal. We will also compare the thermochemical behavior of the Fe, Co, Ni group with the late transition metal alloys.