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

Abstract

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 αp/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.