Determination of Nb–Hf–Si phase equilibria

Phase equilibria of Nb–Hf–Si at 1500 °C have been investigated for the metal-rich end of the ternary phase diagram using scanning electron microscopy, electron probe microanalysis, and electron backscatter diffraction analysis. An isothermal section at 1500 °C was constructed for this ternary system based on experimental data from 11 alloys heat treated at 1500 °C for 100 h. Phase equilibria between the following silicides, Nb(Hf)5Si3, Hf(Nb)5Si3, Nb(Hf)3Si, Hf(Nb)2Si, Hf(Nb)3Si2, Hf(Nb)5Si4, Hf(Nb)Si, Nb(Hf)Si2, and two metal-rich solid solutions, β(Nb,Hf,Si) and α(Hf,Nb,Si) are described.