a1 Universität des Saarlandes and Institut für Neue Materialien, Gebäude 43, D-66041 Saarbrücken, Germany
The importance of the interactions between alloy atoms and topological defects for the thermodynamic properties of nanostructured alloys is pointed out. The McLean model for grain boundary segregation is extended to yield an expression for the total Gibbs free energy of an alloy polycrystal. This provides a simple conceptual basis for a qualitative discussion of the thermodynamic properties of nanocrystalline alloys. It is demonstrated that certain alloy poly- or nanocrystals may reach a metastable state, where the alloy is stable with respect to variation of its total grain boundary area.
(Received January 12 1993)
(Accepted August 24 1993)