Abstract
Titanium and its alloys exhibit advantageous ductility and strength-to-weight ratios, which makes them suitable for use as structural materials in numerous industrial applications. The ω phase has been observed to precipitate during the aging process of titanium alloys, resulting in a loss of ductility. Here we report tensile behavior of bulk polycrystalline ω-titanium with a chemical composition of commercially pure titanium grade 4 and an average grain size of 3.4 μm. We observed that stress-induced ω → α martensitic phase transformation occurs exclusively in the plastic regime. As plastic deformation proceeds, the volume fraction of α-phase increases. The 0.2% offset yield strength, tensile strength, and elongation to failure were determined to be 1130 ± 30 MPa, 1220 ± 30 MPa, and 16 ± 2%, respectively. The present study revealed transformation-induced plasticity in this material. The mechanical properties of this material with the pure titanium composition are comparable to those of a titanium alloy Ti-6Al-4 V. The bulk polycrystalline ω-titanium can potentially be utilized for biomedical applications, such as dental implants.
Data availability
The data that support the findings of this study are available from the corresponding author upon reasonable request.
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Acknowledgements
We thank T. Hanawa, H. Hosoda, A. Holtzheid, T. Nakano, P. Wiedekehr, M. Pawelkiewicz-Koebel, H. Fujii, and M. Goto for discussion. We also thank H. Ichihara, K. Manabe, I. So, J. Li, H. Muto, and H. Ikeda for technical assistance. Synchrotron XRD measurements were conducted at BL16, SAGA-LS (project number: SEI2023C-012, SEI2024B-012). This research was supported by Japan Society for the Promotion of Science, a Grant-in-Aid for Scientific Research on the innovation area “Science of New-Class of Materials Based on Elemental Multiplicity and Heterogeneity (Grant No. 18H05452)” partially to N.N.
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N.N., K.S., F.W., and Z.H. designed the research. N.N., M.M., Y.K., A.F., and Z.H. led the project. N.N., Y.T., and T.Sawahata performed high-pressure synthesis. Y.T. and T.Sawahata performed XRD measurements. Y.T., T.Sawahata, and Z.H. performed tensile tests. K. Tominaga and T.Sekiya performed FESEM-EBSD measurements. K.K. performed TEM observations. N.N. and K.Tokuda performed synchrotron XRD measurements. N.N., M.M., and Z.H. wrote the manuscript with contributions from other authors.
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Nishiyama, N., Tange, Y., Sawahata, T. et al. High tensile strength and transformation-induced plasticity in bulk polycrystalline omega titanium. Sci Rep (2026). https://doi.org/10.1038/s41598-025-33037-z
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DOI: https://doi.org/10.1038/s41598-025-33037-z
