Ultrahigh strength and damage tolerance in a hierarchical-structured titanium alloy

Achieving damage tolerance in structural materials can be challenging due to the need for both high strength and ductility, which are typically incompatible properties. The common post-processing techniques in thermomechanical machining enable us to fabricate metal materials with distinctive microstructures, thereby enhancing the mechanical properties of the materials. We show that a hierarchical-structured titanium (HST) alloy consisting of belt-like α phase (α_b), submicron-scaled oval α phase (α_o), and nano-scaled secondary α phase (α_s) has been designed by employing precision and user-friendly process routes. The hierarchical microstructure performs high strength while preserving respectable ductility. The ultrahigh strength (σ_YS∼1257 MPa and σ_UTS∼1411 MPa)) can be mainly attributed to the grain boundary strengthening served by hierarchical α phase. Moreover, the unique architecture provides excellent resistance to crack propagation, obtaining a large ductility (20%), making it a highly promising structural material for engineering applications.