A Modification of Nb-Rich Portion for Refractory Nb-Ni Alloy Phase Diagram with New Peritectoid Transition

The Nb-rich region of refractory Nb-Ni alloy phase diagram was refined by thermal analysis, long-time annealing experiments, and electron probe microanalysis (EPMA). Both metallography and EPMA results indicate that the Nb2Ni phase is a new stable intermetallic phase with a stoichiometric composition. Thermal analyses show that the peritectoid transition of (Nb) + Nb7Ni6 -> Nb2Ni occurs at the temperature of 1569.7 K. In addition, the powder XRD results suggest that the equilibrium lattice constants of Nb7Ni6, Nb2Ni, and (Nb) phases are a = 4.957 angstrom/c = 27.000 angstrom, a = 11.594 angstrom ,and a = 3.299 angstrom, respectively.

Automated summary

The Nb-rich region of the refractory Nb-Ni alloy phase diagram was investigated using thermal analysis, annealing experiments, and electron probe microanalysis (EPMA). A new stable intermetallic phase Nb2Ni with a stoichiometric composition was identified. The peritectoid transition of (Nb) + Nb7Ni6 to Nb2Ni was observed at a temperature of 1569.7 K. Powder XRD measurements revealed the equilibrium lattice constants of Nb7Ni6, Nb2Ni, and (Nb) phases.