Construction of Ti-Nb-TiCu pseudo-ternary phase diagram.

The aim of this study was to construct a Ti-Nb-Cu ternary phase diagram that plays the role of a map for developing new titanium alloys with excellent machinability and mechanical properties. Fifteen experimental Ti-Nb-Cu ternary alloys composed of Ti-5-30%Nb-2-20%Cu were designed, and ingots made using Ar-arc melting furnace before casting to generate specimen. The alloy castings were evaluated in terms of their microstructures and alloy phases. A Ti-Nb-TiCu pseudo-ternary phase diagram was constructed using X-ray diffractmetry results. Three alloy phases (α-Ti, β-Ti and TiCu) were established within the specimen. Furthermore, the prescence of two-phase coexistence regions (α+TiCu, α+β and β+TiCu), and three-phase coexistence region (α+β+TiCu) was noted. The findings obtained through microstructural observation corresponded well with the constructed phase diagram.