Strain rate dependence of the α to ω phase transition in titanium

Titanium (Ti) is commonly used in industrial applications such as aerospace, automotive and biomedical due to its corrosion resistance and high strength to density ratio. At high pressure (2.9-10.5 GPa), Ti transforms from the hexagonal close packed α phase to the open hexagonal ω phase.[1] This phase transformation of Ti is affected by several factors including (i) the hydrostaticity of the compression, (ii) the presence of impurities, and (iii) the compression rate.[1,2] Regarding compression rate, so far Ti has mostly been compressed using static or shock compression with one intermediate compression rate reported.[3,4] In this work, the dynamic diamond anvil cell (dDAC) coupled with time resolved X-ray diffraction was used to study the α to ω phase transformation of Ti at critical compression rates (0.01 to 3500 GPa/s) between static and shock compression rates. It was found that the onset pressure of the phase transition increased as the compression rate increased under both non-hydrostatic compression (uniaxial loading) and quasi-hydrostatic compression (in a He pressure-transmitting medium). Additionally, the onset of this phase transition was found to be ~4 GPa higher across all compression rates in the quasi-hydrostatic experiments.

[1]          D. Errandonea, Y. Meng, M. Somayazulu, and D. Häusermann, Physica B: Condensed Matter 355, 116 (2005).

[2]          N. Velisavljevic, S. MacLeod, and H. Cynn, in Titanium Alloys - Towards Achieving Enhanced Properties for Diversified Applications (IntechOpen, 2012).

[3]          C. W. Greeff, D. R. Trinkle, and R. C. Albers, Journal of Applied Physics 90, 2221 (2001).

[4]          D. Tomasino and C. S. Yoo, in AIP Conference Proceedings2017), p. 060002.