Microstructure and mechanical properties of a novel titanium alloy with homogeneous (TiHf)5Si3 article-reinforcements

A novel Ti-2Si-2Nb-2Fe-1Hf-1Ta-1W alloy consisting of α phase, retained β phase, and submicron scale (TiHf)₅Si₃ precipitates has been fabricated successfully. The incorporation of Hf in the silicon-containing alloys affects the solidification in a special way. The Hf₅Si₃ particles as inoculants can provide sites for the nucleation of the Ti₅Si₃ phase due to their similar crystal structure, which leads to the formation of (TiHf)₅Si₃ compound phase. A large number of spherical (TiHf)₅Si₃ particles around 800 nm in diameter form and uniformly distribute at α_p/β interfaces. The (TiHf)₅Si₃ precipitates hinder the grain growth of α phase and the movement of the activated dislocations, therefore strengthen the alloy by multi-mechanisms. The alloy exhibits high tension strength (942 MPa) with a high level of plasticity (14%). The good plasticity can be achieved through the homogeneous distribution of (TiHf)₅Si₃ phase together with the refinement for equiaxed α phase.