Ductile Ti-based nanocrystalline matrix composites

High-strength Ti–Nb–Cu–Ni–Al in situ cast composites were prepared via arc-melting and injection casting into a copper mold. The microstructure of the Ti-based alloys consists of a bcc β-Ti type main phase and minor amounts of several nanocrystalline interdendritic phases. The optimization of the Ti-based alloy composition is performed to achieve both high strength and high ductility. The best combination of strength and ductility was found for a copper mold cast (TiNb)79(CuNiAl)21 alloy, which exhibits a fracture strength of more than 2000 MPa coupled with a plastic strain of 30%. Also the arc-melted ingot of this alloy exhibits similar mechanical properties compared to its mold cast counterpart. These features significantly improve the mechanical behavior of such composites and open the possibility of obtaining tailored mechanical properties by controlling composition and solidification conditions.