Mapping of the Nb-Cr-Ti phase diagram using diffusion multiples

A high-efficiency diffusion-multiple approach was employed to map the phase diagram of the Nb-Cr-Ti ternary system which is critical for the design of niobium silicide-based composites. These composites have high potential as a replacement for Ni-base superalloys for jet engine applications. The formation of the Laves phase and alloying with Ti are critical for the high oxidation resistance of the composites and the Nb-Cr-Ti system serves as the base for understanding the Laves phase formation and Ti alloying. Three isothermal sections at 1000, 1150 and 1200 C were constructed from the results obtained from diffusion multiples using scanning electron microscopy, electron probe microanalysis, and electron backscatter diffraction. The results help to define the relative stability of the C15 and C36 Laves phases in the Nb-Cr-Ti ternary system. (orig.)