Achieving superior strength-ductility in TiBw/Ti-6Al-4V composites via in-situ Ti2Ni nano-precipitation

The pursuit of enhanced strength and ductility in Ti alloys and their composites represents a significant goal and formidable challenge in the realm of engineering applications. Herein, we have designed and fabricated a novel Ti2Ni nano precipitates reinforced TiBw/Ti-6Al-4V composites with superior strength and ductility using spark plasma sintering and hot rolling technology. The microstructure of the composite contains equiaxial alpha-Ti phase and beta-Ti phase, with the in-situ synthesized TiBw distributed along grain boundaries, and nano-scaled Ti2Ni precipitates distributed in the beta-Ti phase. The (TiBw+Ti2Ni)/Ti-6Al-4V composite exhibits an ultimate tensile strength of 1469 MPa, which is 1/4 higher than that of the Ti-6Al-4V alloy (1158 MPa), and even superior to that of many wrought high-strength Ti alloys and composites, while it still remains an elongation of 6.4 %. This superior mechanical property is mainly attributed to significant grain-refinement strengthening and precipitation strengthening induced by Ti2Ni nano precipitates. This work proposes a new approach to achieve a good balance between the strength and ductility of titanium matrix composites.