In Situ Synchrotron X-ray Analysis: Application of High-Pressure Sliding Process to Ti Allotropic Transformation

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-ray. The phase transformation from a phase to to phase occurred at a pressure of similar to 4.5 GPa. Straining by the HPS processing was effective to promote the transformation to the to phase and to maintain the to phase even at ambient pressure. The reverse transformation from to phase to a phase occurred at a temperature of similar to 110? under ambient pressure, while under higher pressure as similar to 4 GPa, the to phase remained stable even at similar to 170? covered in this study. It was suggested that the reverse transformation from the to phase to the a phase is controlled by thermal energy.