Microstructure and deformation mechanism of ultra-high strength Ti-Fe-Nb-Sn alloys

To overcome the strength limitations of traditional titanium alloys, this study incorporated small amounts of Nb and Sn elements into Ti-Fe-based alloys to create Ti-Fe-Nb-Sn alloys with theoretical composition near the Fe vector on the Bo-Md map. The microstructures of vacuum self-consumed melted Ti-Fe-Nb-Sn alloys consisted mainly of dendritic β phase, with minor amounts of α-Ti + Ti 3 Sn and TiFe phases distributed within and between dendrites. After room temperature compression, the Ti-Fe-Nb-Sn alloys did not fracture completely at 70% compression and achieved a final strength exceeding 3500 MPa. During compression, grain boundary cracks, slip plane cracks, and internal cracks in dendrite structures formed. However, due to the alloy's exceptional plastic toughness, crack tips were passivated without expansion. The Ti-Fe-Nb-Sn alloys exhibited excellent plasticity and ultra-high strength.