Complexion-mediated martensitic phase transformation in Titanium

• Published in: Nature communications 2017-02, Vol.8 (1), p.14210-14210, Article 14210
• Main Authors: Zhang, J., Tasan, C. C., Lai, M. J., Dippel, A. -C., Raabe, D.
• Format: Article
• Language: English
• Subjects: 639/301/1023/1026; 639/301/119; Cooling; Deformation; Humanities and Social Sciences; Interfaces; Mechanical properties; multidisciplinary; Phase transitions; Science; Science (multidisciplinary); Temperature; Titanium alloys
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms14210

The most efficient way to tune microstructures and mechanical properties of metallic alloys lies in designing and using athermal phase transformations. Examples are shape memory alloys and high strength steels, which together stand for 1,500 million tons annual production. In these materials, martensite formation and mechanical twinning are tuned via composition adjustment for realizing complex microstructures and beneficial mechanical properties. Here we report a new phase transformation that has the potential to widen the application window of Ti alloys, the most important structural material in aerospace design, by nanostructuring them via complexion-mediated transformation. This is a reversible martensitic transformation mechanism that leads to a final nanolaminate structure of α ″ (orthorhombic) martensite bounded with planar complexions of athermal ω ( a – ω , hexagonal). Both phases are crystallographically related to the parent β (BCC) matrix. As expected from a planar complexion, the a – ω is stable only at the hetero-interface. One way of tuning mechanical properties of alloys lies in utilizing athermal phase transitions. Here authors report a complexion-mediated martensitic transformation in Ti alloys yielding a nanolaminate structure of martensite bounded by planar complexions, promising new strategies for the design of high strength Ti alloys.