DETERMINATION OF INTERCHANGE ENERGIES FROM THERMODYNAMIC AND STRUCTURAL DATA

Abstract

The numerical values of the interchange energies W(1), W(2) between nearest and aext-nearest neighbours in bcc and fcc solid solutions can be determined from energy measurements (e.g. enthalpy of formation) and from structural data (e.g. critical temperature of long range order). If the energy data do not refer to bcc (or fcc) standard states they must be appropriately converted. If critical temperatures are used short range order effects must be considered. For both fcc and bcc solid solutions W(1) and W(2) are found of the same order of magnitude. In the fcc alloys studied here W(2) is found of opposite sign of W(1). The consequences for the phase diagram are discussed.