Microstructure evolution of as-cast Nb-Ti-C alloys

Nb-Ti-C alloys with different Ti contents (4%–16%, mole fraction) were fabricated by vacuum non-consumable arc-melting method. The results indicate that the alloys contain niobium solid solution (Nbss), carbides (Nb2C, (Nb, Ti)C) and eutectic of Nbss/MC. Carbides in the Nb-Ti-C alloys change from Nb2C to (Nb, Ti)C with the increase of titanium content. Microstructures in the as-cast state include primary plate-like Nb2C, eutectic of Nbss/Nb2C, Nbss and secondary needle-like Nb2C in Nb-5Ti-4C alloy, and other microstructures are primary Nbss, eutectic of Nbss/(Nb, Ti)C. Morphology of carbides are changed apparently through adding different Ti contents, and morphology of Nbss changes from the cellular structure to dendrite.