Phase equilibrium in the cerium-poor Ce–Ni–Cu system

In the framework of preparing metallic substrates for high temperature superconductors of the second generation, the Ce–Ni–Cu system in Ce-poor field has been studied by means of DTA/TG, X-ray diffraction, SEM with EDX attachment and optical microscope. For the solid state equilibrium, the existence of a continuous solid solution Ce(Ni1−xCux)5 has been confirmed and it was found that this solid solution extends in poor Ce compositions. No ternary phase could be evidenced in the investigated field. CeCu6 was found to dissolve up to 5 at.% Ni. The cerium solubility in the (Ni,Cu) solid solution is less than 0.5 at.%. At high temperatures, for the equilibrium implying a liquid phase, a ternary eutectic reaction L ↔ Ce(Ni,Cu)6 + Ce(Ni,Cu)5 + (Ni,Cu) occurs at T = 871 °C for Ce0.10Ni0.07Cu0.83, i.e for a Ce composition 1 at.% higher than in the binary systems. Finally, the polythermal section of the system has been estimated and the isoplethic sections with the 16.7 at.% Ce, 14.3 at.% Ce and 9 at.% Ce are proposed.