Determination of Nb-Hf-Si phase equilibria

Phase equilibria of Nb-Hf-Si at 1500 degreesC have been investigated for th e metal-rich end of the ternary phase diagram using scanning electron micro scopy, electron probe microanalysis, and electron backscatter diffraction a nalysis. An isothermal section at 1500 degreesC was constructed for this te rnary system based on experimental data from I I alloys heat treated at 150 0 degreesC for 100 h. Phase equilibria between the following silicides, Nb( Hf)(5)Si-3, Hf(Nb)(5)Si-3, Nb(Hf)(3)Si, Hf(Nb)(2)Si. Hf(Nb)(3)Si-2, Hf(Nb)( 5)Si-4, Hf(Nb)Si, Nb(Hf)Si-2, and two metal-rich solid solutions, beta (Nb, Hf.Si) and alpha (Hf,Nb,Si) are described. (C) 2001 Elsevier Science Ltd. A ll rights reserved.