Isothermal sections of the Co-Nb-Ni phase diagram at 1200 and 1375 K

The isothermal sections of the Co-Nb-Ni system were constructed at 1375 K and 1200 K by investigations of equilibrated alloys with the use of electron probe microanalysis (EPMA), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD) and differential thermal analysis (DTA). In the Co-Nb-Ni system, phases take part in the following three-phase equilibria: (α+γ+λ), (α+λ+μ), (γ+λ+λ′) at 1375 K and (α+γ+λ), (α+λ+μ), (α'+γ+λ) at 1200 K. The α′-phase of the binary Co-Nb system at 1200 K has the composition Co3Nb and crystallises with the Mg3Cd-type of the crystal structure.