A CONTRIBUTION TO THE TERNARY COPPER-MAGNESIUM-NICKEL PHASE-DIAGRAM

The ternary Cu-Mg-Ni phase diagram has been studied by differential th ermal analyses, X-ray powder diffraction and isopiestic vapour pressur e measurements, Three different isopleths with constant x(Cu)/x(Ni) ra tios of 2.0, 1.0 and 0.5, and one with a constant magnesium content of 71 at.% were constructed from these measurements. Together with liter ature information it was possible to define the four invariant four-ph ase equilibria in the system with respect to the temperature and compo sitions of the participating phases, and to derive the monovariant rea ction lines on the liquidus surface. Furthermore, it was confirmed tha t Mg2Ni dissolves up to about 25 at.% Cu at 450 degrees C.