ORIGINAL PAPER Phase relations in the Nb–Ni–Cr system at 1,100 C

The Author(s) 2012. This article is published with open access at Springerlink.com Abstract The isothermal cross section through the ternary phase diagram Nb–Ni–Cr at 1,100 C was con-structed by means of diffusion couples and equilibrated alloys. It was found that nearly 28 at. % of Cr can be dis-solved in the l phase (Nb7Ni6) at this temperature, and the solubility of chromium in NbNi3 is approximately 5 at.%. Under these circumstances the low-temperature (cubic) modification of the NbCr2 Laves phase can dissolve up to 6 at. % of nickel, but further increase of the Ni content (up to approximately 10 at.%) stabilizes the hexagonal (high-temperature) modification of the Laves phase. The pres-ence of this pseudo-ternary compound which is in equilibrium with all binary intermetallics and body-centred cubic (BCC) Nb- and Cr-based solid solutions largely determines the topology of the isotherm at 1,100 C. The formation of this phase was also observed in the reaction zone between Nb and Ni–Cr solid solution when chromium concentration exceeded 15 at.%