Experimental investigation of phase equilibria in the Nb–Ni–Si refractory alloy system at 1323 K

Abstract

Phase equilibria in the Nb–Ni–Si ternary system were experimentally determined at 1323 K and 1473 K using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) techniques. The 1323 K isothermal section of the phase diagram was proposed in combination with previous knowledge of phase stabilities in the system at 1073 K. The results at 1473 K, on the other hand, positively allowed the identification of three new intermetallics phases, not present at lower temperatures, which still need to be crystallographically characterized. The new phases are found in equilibrium either with the Nb5Si3 compound or with the Nb-rich bcc solid solution, which are characterized by very high melting temperatures.