On the role of atomic thermal vibrations in binary-alloy thermodynamics

An ab initio approach is advanced for the thermodynamical properties invest igations of disordered binary alloys, Configurational and vibrational degre es of freedom are considered on the microscopic level in the grand partitio n sum calculations. Summing over the vibrational and configurational states of an alloy is performed within the reference system approach and the coll ective variables method, respectively. An equation defining the alloy free energy is obtained. The role of the atomic thermal vibrations in the binary -alloy thermodynamics and their relationship with the configurational effec ts are discussed. Conditions when the configurational and vibrational effec ts can be treated separately is formulated. (C) 2001 Elsevier Science B.V. All rights reserved.