Order-disorder transformations in Ni-Al alloys

摘要

A brief introduction to the first-principles electronic theory of alloy phase stability is presented and applied to the study of phase equilibria in Ni-rich Ni-Al alloys. The thermodynamics of phases based on the fcc and bcc lattices are treated within various approximate solutions to the using Hamiltonian bv means of the Cluster Variation Method and phase diagrams are computed. Particular attention is paid to the existence of the ordered phase at Ni(sub 5)Al(sub 3) at low temperatures. It must be noted that only fcc- and bcc-based phases are considered and that the liquid alloy is ignored.