Ultrastrong titanium alloy based on sub-10-nm stacking bands via additive manufacturing

 

Lightweight alloys that combine high mechanical strength with good ductility are essential for advanced structural applications. Among them, titanium (Ti) alloys stand out for their high specific strength, corrosion resistance, and versatile phase stability, making them particularly attractive for nanoscale structural engineering.

Nanostructured metals exhibit exceptional mechanical strength and functional properties associated with deformation incompatibility and a high density of grain boundaries. However, producing fully nanostructured bulk metals remains a challenge, particularly when components with complex geometries are required for practical applications. Established methods such as ion sputtering, electrodeposition, and severe plastic deformation have demonstrated the feasibility of producing metals with nanoarchitectures and outstanding properties. Nevertheless, the gap between laboratory achievements and industrial implementation remains considerable.

A group of researchers in China fabricated an alloy consisting of titanium (Ti) combined with 7.5% aluminum (Al) and 3.3% chromium (Cr). Using bottom-up additive manufacturing (AM) and laser powder bed fusion (LPBF), an alloy was obtained with ultrahigh mechanical strength. The alloy composition and processing parameters were optimized using machine learning and high-throughput experimentation. In LPBF, programmed laser-scanning strategies selectively melt and solidify metal powder layer by layer, subjecting the components to extreme thermal gradients, high cooling rates, and repeated thermal cycles.

The influence of the alloying elements on the interfacial energies of the Ti alloy was investigated using ab initio calculations based on density functional theory (DFT).

The resulting nanostructure, characterized by stacking bands narrower than 10 nm, gives the Ti alloy a yield strength of approximately 1.5 GPa, a tensile strength exceeding 1.7 GPa, a uniform elongation of approximately 7.5%, and a specific strength of approximately 380 MPa·cm³·g⁻¹.

The developed Ti alloy combines high strength, ductility, and scalability in manufacturing, offering a promising combination of properties for structural applications. This approach opens new possibilities for developing metals with improved mechanical properties and greater manufacturability, even for the most demanding applications.

For further information go to: nature materials