The validity of the Neumann-Kopp rule 1

Molar heat capacities at constant pressure of Al90Fe7Nb3 master alloy and both as- quenched and crystallized ribbons were determined by the step-by-step method using differential scanning calorimetry from 310 to 1080 K. The experimental temperature dependencies have been analytically fitted by polynomial Cp(T) = a + bT + cT 2 + dT -1 + eT -2 . The a - e polynomial parameters have also been physically appraised and correlated with the measurements. The validity of the Neumann-Kopp rule relating the heat capacities of the multiphase Al90Fe7Nb3 alloy and its three equilibrium phases, namely Al, Al3Fe and Al3Nb, has been tested. During the workshop Thermophysics 2001 (1), the step-by-step differential scanning calorimetry was introduced. The reproducibility and uncertainty of the molar heat capacity data under normal pressure, Cp(T), for metal standards were tested. The temperature dependence of Cp(T) for one compound was determined and fitted by polynomial from 310 to 1473 K. In this paper, the Cp(T) measurements of the bulk multiphase Al90Fe7Nb3 master alloy and also the as-quenched and crystallized ribbon up to 1080 K is presented. The molar heat capacities of the heterogeneous bulk and ribbon alloys are related to the heat capacities of their phases. The rapidly quenched Al-based intermetallics are interesting new materials because of their heterogeneous amorphous or nanocrystalline microstructures and associated outstanding mechanical properties.