Abstract
Ti-alloys represent the principal structural materials in both aerospace development and metallic biomaterials. Key to optimizing their mechanical and functional behaviour is in-depth know-how of their phases and the complex interplay of diffusive vs. displacive phase transformations to permit the tailoring of intricate microstructures across a wide spectrum of configurations. Here, we report on structural changes and phase transformations of Ti–Nb alloys during heating by in situ synchrotron diffraction. These materials exhibit anisotropic thermal expansion yielding some of the largest linear expansion coefficients (+ 163.9×10−6 to −95.1×10−6 °C−1) ever reported. Moreover, we describe two pathways leading to the precipitation of the α-phase mediated by diffusion-based orthorhombic structures, α″lean and α″iso. Via coupling the lattice parameters to composition both phases evolve into α through rejection of Nb. These findings have the potential to promote new microstructural design approaches for Ti–Nb alloys and β-stabilized Ti-alloys in general.
Highlights
Ti-alloys represent the principal structural materials in both aerospace development and metallic biomaterials
Aside from reaching giant values in case of Nb-rich alloy formulations, the thermal expansion rates of the present alloys can be adjusted across a wide range by modifying their composition
This represents an advantage over many ceramic materials which often show rather limited controllability of their thermal expansion[38]
Summary
Ti-alloys represent the principal structural materials in both aerospace development and metallic biomaterials Key to optimizing their mechanical and functional behaviour is in-depth know-how of their phases and the complex interplay of diffusive vs displacive phase transformations to permit the tailoring of intricate microstructures across a wide spectrum of configurations. Certain alloy compositions display low Young’s moduli (E) below 80 GPa after rapid cooling[4, 5], providing suitable starting points for the development of novel low-modulus alloys for load-bearing implant applications Due to their high strength to density ratio β-stabilized Ti-alloys have become increasingly used for various aerospace applications such as airframes and landing gears[3]. Due to the thermoelastic martensitic transformation of the body centred cubic (bcc) β-phase to orthorhombic martensite α′′ This alloy family demonstrates shape memory (SM) behaviour and superelasticity (SE)[6, 7]. The transformation and precipitation pathways occurring during aging decide the morphology, size and arrangement of the precipitating products[11, 12]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
