Relative stability of ordered phases in bcc Cu-Al-Zn

F. LANZINI; R. ROMERO; G. H. RUBIOLO

CALPHAD-COMPUTER COUPLING OF PHASE DIAGRAMS AND THERMOCHEMISTRY

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2011 vol. 35 p. 396 - 402

0364-5916

The relative stability of the short range ordered and different long range ordered structures in body centered cubic Cu-Al-Zn is studied by means of the Cluster Variation Method in the Irregular Tetrahedron approximation (IT-CVM). The energetic parameters (constant pair interchange energies for first and second neighbor pairs) used in our calculations have been extracted from experimental order-disorder transition temperatures. It is shown that the use of constant pair interchange energies allows accuratereproduction of the experimental transition temperatures in the binary subsystems Cu-Al and Cu-Zn. Several isothermal sections of the ternary system at temperatures between 600 and 900 K have beencalculated. The two-phase field for compositions around Cu3Al in the ternary system was determined: It was found that such region extends to around 15 at.% Zn in the pseudo-binary Cu0.76-0.5x - Al0.24-0.5x - Znx .