The isothermal section of the Co–Ni–Nb ternary system at 1123 K determined by diffusion triple technique

An isothermal section of the Co–Ni–Nb system at 1123 K was experimentally determined using diffusion triple technique together with electron probe microanalysis (EPMA). Two binary compounds, Ni6Nb7 and Co7Nb6 form a continuous solid solution (Ni,Co)6Nb7 in the ternary. Ni can partially substitute Co in Co2Nb and Nb in Co3Nb. Co can partially substitute Ni in Ni3Nb. One ternary phase named as “X” has been observed with homogeneity range covering 20–68 at.% Co and 23–26 at.% Nb. Furthermore, five three-phase equilibria, Co3Nb + Co2Nb + X, X + (Ni,Co)6Nb7 + Co2Nb, X + Co3Nb + γ(Co,Ni), Ni3Nb + X + (Ni,Co)6Nb7 and Ni3Nb + X + γ(Co,Ni) have been determined in this isothermal section.