Phase equilibria of the Nb–Si-Gd ternary system at 1273 K

Abstract

The phase equilibria of the Nb–Si-Gd ternary system at 1273 K in all the composition ranges were investigated by X-ray diffraction (XRD), electron probe microanalysis (EPMA), and Scanning electron microscopy (SEM) equipped with Energy dispersive spectroscopy (EDS). The isothermal section comprises 12 single-phase regions, 22 two-phase regions, and 11 three-phase regions. The existing of Nb3Si phase was confirmed at 1273 K by couple diffusion. A new ternary compound Gd2Nb3Si4 was discovered and its crystal structure was analyzed by the Rietveld method with Rwp = 2.11%, Rp = 1.54%, Rexp = 0.75%. It belongs to the space group P41212 (No.92) with the lattice parameter a = b = 6.99048 Å, c = 12.94393 Å, α = β = γ = 90°.