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

Abstract

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 (αb), submicron-scaled oval α phase (αo), and nano-scaled secondary α phase (αs) has been designed by employing precision and user-friendly process routes. The hierarchical microstructure performs high strength while preserving respectable ductility. The ultrahigh strength (σYS∼1257 MPa and σUTS∼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.