High-tensile-strength and ductile novel Ti-Fe-N-B alloys reinforced with TiB nanowires

In this study, we designed and fabricated high-performance Ti-Fe-N-B alloys by sintering a blend of Ti powder, Fe powder and BN nanopowder using spark plasma sintering. During sintering, TiB nanowires nucleated from the surfaces of Ti powder particles on which the BN nanoparticles were dispersed, and then grew into the nearby Ti matrix forming a three-dimensional (3D) network-woven architecture throughout the Ti matrix. The TiB nanowires were about 10-30 µm in length and 50-200 nm in diameter after sintering. Their existence suppressed the formation of the continuous α-Ti phase along the β-Ti grain boundaries and refined the microstructure of the Ti matrix. A large quantity of α-Ti nanoplates precipitated along the planes (110) β-Ti in the Ti-Fe-N-B alloys. The as-sintered Ti-4.5Fe-0.14N-0.11B alloy achieved a high tensile strength of 1176 MPa with a significant tensile elongation of 10.4%, which satisfied the requirements for the tensile properties of mill-annealed Ti6Al4V in the solution-treated and aged (STA) condition. The TiB nanowires, α-Ti nanoplates, Fe solute atoms, and N solute atoms in the matrix all contributed to the high tensile strength.