<i>In Situ</i> Synchrotron X-ray Analysis: Application of High-Pressure Sliding Process to Ti Allotropic Transformation
Zenji Horita, Daisuke Maruno, Yukimasa Ikeda, Takahiro Masuda, Yongpeng Tang, Makoto Arita, Yuji Higo, Yoshinori Tange, Yasuo Ohishi
Abstract
In this study, severe plastic deformation through high-pressure sliding (HPS) was applied for in situ high-energy X-ray diffraction analysis at SPring-8 in JASRI (Japan Synchrotron Radiation Research Institute). Allotropic transformation of pure Ti was examined in terms of temperatures, pressures and imposed strain using a miniaturized HPS facility. The true pressure applied on the sample was estimated from the peak shift. Peak broadening due to local variation of pressure was reduced using white X-rays. The phase transformation from α phase to ω phase occurred at a pressure of ∼4.5 GPa. Straining by the HPS processing was effective to promote the transformation to the ω phase and to maintain the ω phase even at ambient pressure. The reverse transformation from ω phase to α phase occurred at a temperature of ∼110°C under ambient pressure, while under higher pressure as ∼4 GPa, the ω phase remained stable even at ∼170°C covered in this study. It was suggested that the reverse transformation from the ω phase to the α phase is controlled by thermal energy.