Tie lines in a two-phase region in the Cu-Ni-Zn system

The positions of the f.c.c. + b.c.c. two-phase region and the f.c.c. + b.c.c. + tetragonal three-phase region of the Cu-Ni-Zn system have been determined. The position of the latter differs significantly from that determined by Schramm & Vaupel [Metallwirtsch. (1936), 15, 723-726]. Unit-cell parameters measured by X-ray powder photography enabled tie lines in the two-phase region to be drawn. Hence information about the free-energy surfaces has been derived.