Ultrahigh strength – ductility in Ti–6Al–4V composites with high-activity graphene-induced in-situ TiC and coherent nanophases

Achieving ultra-high strength and ductility of titanium alloys possesses great potential for structural applications in the aerospace and military, yet there is a great challenge for breaking the trade-off barrier of these two properties. In this study, large elongation of ∼10 % and ultra-high tensile strengths of 1510 MPa were obtained in a titanium-based composite. We designed this superior composite based on nanoscale coherent αʹʹ precipitation within near-equiaxed β-Ti as well as micro-scale TiC network architectures along grain boundaries. These in-situ formed triangular αʹʹ coherent precipitates and TiC mainly contributed to the strengthening, while the extremely large elongation resulted from coherent β/αʹʹ interfaces and strain-induced coherent αʹʹ nanotwins. We demonstrated that this composite was easily fabricated using a simple powder metallurgy followed by a hot rolling process. This work can contribute to the design of duplex titanium-based composites as well as other structural materials with exceptional mechanical properties for broad applications.