Abstract
Two-phase titanium-based alloys are widely used in aerospace and biomedical applications, and they are obtained through phase transformations between a low-temperature hexagonal closed-packed α-phase and a high-temperature body-centred cubic β-phase. Understanding how a new phase evolves from its parent phase is critical to controlling the transforming microstructures and thus material properties. Here, we report time-resolved experimental evidence, at sub-ångström resolution, of a non-classically nucleated metastable phase that bridges the α-phase and the β-phase, in a technologically important titanium–molybdenum alloy. We observed a nanosized and chemically ordered superstructure in the α-phase matrix; its composition, chemical order and crystal structure are all found to be different from both the parent and the product phases, but instigating a vanishingly low energy barrier for the transformation into the β-phase. This latter phase transition can proceed instantly via vibrational switching when the molybdenum concentration in the superstructure exceeds a critical value. We expect that such a non-classical phase evolution mechanism is much more common than previously believed for solid-state transformations.
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All data generated or analysed during this study are included in the published article and Supplementary Information, and are available from the corresponding authors upon reasonable request.
References
Porter, D. A., Easterling, K. E. & Sherif, M. Phase Transformations in Metals and Alloys (CRC Press, 2009).
Banerjee, S. & Mukhopadhyay, P. Phase Transformations Examples from Titanium and Zirconium Alloys (Elsevier Science, 2007).
Cahn, J. W. & Hilliard, J. E. Free energy of a nonuniform system. III. Nucleation in a two component incompressible fluid. J. Chem. Phys. 31, 688–699 (1959).
Chen, L.-Q. & Khachaturyan, A. G. Kinetics of virtual phase formation during precipitation of ordered intermetallics. Phys. Rev. B 46, 5899–5905 (1992).
Poduri, R. & Chen, L.-Q. Non-classical nucleation theory of ordered intermetallic precipitates—application to the Al-Li alloy. Acta Mater. 44, 4253–4259 (1996).
De Yoreo, J. J. et al. Crystallization by particle attachment in synthetic, biogenic, and geologic environments. Science 349, aaa6760 (2015).
Gebauer, D. & Cölfen, H. Prenucleation clusters and non-classical nucleation. Nano Today 6, 564–584 (2011).
Lee, J., Yang, J., Kwon, S. G. & Hyeon, T. Nonclassical nucleation and growth of inorganic nanoparticles. Nat. Rev. Mater. 1, 16034 (2016).
Momeni, K. & Levitas, V. I. Propagating phase interface with intermediate interfacial phase: phase field approach. Phys. Rev. B 89, 184102 (2014).
Zhang, L., Ren, W., Samanta, A. & Du, Q. Recent developments in computational modelling of nucleation in phase transformations. npj Comput. Mater. 2, 16003 (2016).
Gránásy, L. et al. Phase-field modeling of crystal nucleation in undercooled liquids – a review. Prog. Mater. Sci. 106, 100569 (2019).
Lutsko, J. F. How crystals form: a theory of nucleation pathways. Sci. Adv. 5, eaav7399 (2019).
Myerson, A. S. & Trout, B. L. Nucleation from solution. Science 341, 855–856 (2013).
Lupulescu, A. I. & Rimer, J. D. In situ imaging of silicalite-1 surface growth reveals the mechanism of crystallization. Science 344, 729–732 (2014).
Ou, Z., Wang, Z., Luo, B., Luijten, E. & Chen, Q. Kinetic pathways of crystallization at the nanoscale. Nat. Mater. 19, 450–455 (2020).
Houben, L., Weissman, H., Wolf, S. G. & Rybtchinski, B. A mechanism of ferritin crystallization revealed by cryo-STEM tomography. Nature 579, 540–543 (2020).
Gebbie, M. A. et al. Experimental measurement of the diamond nucleation landscape reveals classical and nonclassical features. Proc. Natl Acad. Sci. USA 115, 8284–8289 (2018).
Fei, L. et al. Observable two-step nucleation mechanism in solid-state formation of tungsten carbide. ACS Nano 13, 681–688 (2019).
Leyens, C. & Peters, M. (eds) Titanium and Titanium Alloys: Fundamentals and Applications (Wiley‐VCH Verlag, 2003).
Lütjering, G. & Williams, J. Titanium (Springer-Verlag, 2007).
Geetha, M., Singh, A. K., Asokamani, R. & Gogia, A. K. Ti based biomaterials, the ultimate choice for orthopaedic implants – a review. Prog. Mater. Sci. 54, 397–425 (2009).
Hou, H. et al. Fatigue-resistant high-performance elastocaloric materials made by additive manufacturing. Science 366, 1116–1121 (2019).
Nag, S. et al. Non-classical homogeneous precipitation mediated by compositional fluctuations in titanium alloys. Acta Mater. 60, 6247–6256 (2012).
Boyne, A. et al. Pseudospinodal mechanism for fine α/β microstructures in β-Ti alloys. Acta Mater. 64, 188–197 (2014).
Meiners, T., Frolov, T., Rudd, R. E., Dehm, G. & Liebscher, C. H. Observations of grain-boundary phase transformations in an elemental metal. Nature 579, 375–378 (2020).
Rabkin, E. Boundaries transformed in pure metals. Nature 579, 350–351 (2020).
Gogia, A. K. High-temperature titanium alloys. Def. Sci. J. 55, 149–173 (2005).
Wang, G. et al. Microstructure and mechanical properties of electron beam welded titanium alloy Ti-6246. J. Mater. Sci. Technol. 34, 570–576 (2018).
Dutt, A. K. et al. A novel nano-particle strengthened titanium alloy with exceptional specific strength. Sci. Rep. 9, 11726 (2019).
Murry, J. L. The Mo-Ti (molybdenum-titanium) system. Bull. Alloy Phase Diagr. 2, 185–192 (1981).
Pennycook, S. J. & Nellist, P. D. Scanning Transmission Electron Microscopy Imaging and Analysis (Springer, 2002).
Burgers, W. G. On the process of transition of the cubic-body-centered modification into the hexagonal-close-packed modification of zirconium. Physica 1, 561–586 (1934).
Lonardelli, I. et al. In situ observation of texture evolution during α→β and β→α phase transformations in titanium alloys investigated by neutron diffraction. Acta Mater. 55, 5718–5727 (2007).
Furuhara, T., Ogawa, T. & Maki, T. Atomic structure of interphase boundary of an a precipitate plate in a β Ti-Cr alloy. Philos. Mag. Lett. 72, 175–183 (1995).
Menon, E. S. K. & Aaronson, H. I. Morphology, crystallography and kinetics of sympathetic nucleation. Acta Metall. 35, 549–563 (1987).
Aaronson, H. I. et al. Sympathetic nucleation: an overview. Mater. Sci. Eng. B 32, 107–123 (1995).
Hickman, B. S. The formation of omega phase in titanium and zirconium alloys: a review. J. Mater. Sci. 4, 554–563 (1969).
Devaraj, A. et al. Experimental evidence of concurrent compositional and structural instabilities leading to ω precipitation in titanium–molybdenum alloys. Acta Mater. 60, 596–609 (2012).
Zhao, X., Niinomi, M., Nakai, M. & Hieda, J. Beta type Ti-Mo alloys with changeable Young’s modulus for spinal fixation applications. Acta Biomater. 8, 1990–1997 (2012).
Li, M. & Min, X. Origin of omega-phase formation in metastable beta-type Ti-Mo alloys: cluster structure and stacking fault. Sci. Rep. 10, 8664 (2020).
Luo, J., Cheng, H., Asl, K. M., Kiely, C. J. & Harmer, M. P. The role of a bilayer interfacial phase on liquid Metal embrittlement. Science 333, 1730–1733 (2011).
Yu, Z. et al. Segregation-induced ordered superstructures at general grain boundaries in a nickel-bismuth alloy. Science 358, 97–101 (2017).
Jiang, S. et al. Ultrastrong steel via minimal lattice misfit and high-density nanoprecipitation. Nature 544, 460–464 (2017).
Raabe, D., Sander, B., Friák, M., Ma, D. & Neugebauer, J. Theory-guided bottom-up design of β-titanium alloys as biomaterials based on first principles calculations: theory and experiments. Acta Mater. 55, 4475–4487 (2007).
Sahara, R., Emura, S., Ii, S., Ueda, S. & Tsuchiya, K. First-principles study of electronic structures and stability of body-centered cubic Ti–Mo alloys by special quasirandom structures. Sci. Technol. Adv. Mater. 15, 035014 (2014).
Barzilai, S., Toher, C., Curtarolo, S. & Levy, O. Molybdenum-titanium phase diagram evaluated from ab initio calculations. Phys. Rev. Mater. 1, 023604 (2017).
Nakajima, H. & Koiwa, M. Diffusion in titanium. ISIJ Int. 31, 757–766 (1991).
Chen, L. et al. Nanoscale behavior and manipulation of the phase transition in single-crystal Cu2Se. Adv. Mater. 31, 1804919 (2019).
Kresse, G. & Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169–11186 (1996).
Blöchl, P. E. Projector augmented-wave method. Phys. Rev. B 50, 17953–17979 (1994).
Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996).
Henkelman, G., Uberuaga, B. P. & Jónsson, H. A climbing image nudged elastic band method for finding saddle points and minimum energy paths. J. Chem. Phys. 113, 9901–9904 (2000).
Acknowledgements
We acknowledge Y.-Z. Wang and J. Xu for useful discussions. Q.Y. acknowledges support by the Natural Science Foundation of China (51671168 and 51871197), the National 111 Project under grant no. B16042 and the State Key Program for Basic Research in China under grant no. 2017YFA0208200. W.Z. acknowledges support by the National 111 Project 2.0 under grant no. BP2018008, the Xi’an Jiaotong University high-performance computing platform and the International Joint Laboratory for Micro/Nano Manufacturing and Measurement Technologies at Xi’an Jiaotong University. E.M. acknowledges Xi’an Jiaotong University for hosting his work. L.-q.C. acknowledges the generous support from the Hamer Foundation through the Hamer Professorship in the Department of Materials Science and Engineering at Penn State. We thank beamline BL14B1 of the Shanghai Synchrotron Radiation Facility for providing the beamtime. The financial support is from the National Science Foundation of China (NSFC grant U1932201).
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Q.Y. and W.Z. designed the research. X.F., Q.Y., B.Z., Q.Z. and L.G. performed STEM and in situ experiments. Y.Z. and W.-Z.Z. synthesized alloys. X.-D.W., W.Z., S.S. and J.-J.W. performed theoretical modelling and ab initio simulations. W.W., Q.Y. and X.F. performed synchrotron X-ray diffraction experiments. Z.Z., Q.Y., W.Z., E.M. and L.-q.C. contributed to data analysis and discussions. Q.Y., W.Z. and E.M. wrote the paper, with input from their coauthors and especially L.-q.C.
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Supplementary Figs. 1–10 and caption for Supplementary Video 1.
Supplementary Video 1
The in situ HRTEM observation of the transformation. The blue dashed line marks the position of the pre-existing phase boundary. The red arrows point to the sites of nucleation.
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Fu, X., Wang, XD., Zhao, B. et al. Atomic-scale observation of non-classical nucleation-mediated phase transformation in a titanium alloy. Nat. Mater. 21, 290–296 (2022). https://doi.org/10.1038/s41563-021-01144-7
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DOI: https://doi.org/10.1038/s41563-021-01144-7
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