Higher APF hexagonal titanium formation and related phenomena by shearing α-titanium at high pressure at room temperature

Abstract

Titanium is one of the most extensively used metals. Its structural change at high pressure, however, has not been fully clarified yet because of its relatively short history of extensive use. Alpha-titanium was, therefore, sheared at high pressure at room temperature to get the information caused by this process. This paper presents three findings occurred by the process mentioned above. They are the formation of hexagonal titanium with a higher atomic packing factor than hcp, i.e. new titanium-allotrope formation, the dependence of the ω-titanium ratio after the pressure release on the pressure-raising speed and cubic TiO1.04 formation without quenching. The first and the second findings will provide useful information to make mechanically strong titanium; ω-titanium is brittle and it is important to decrease its proportion. The last finding adds new information to the traditionally accepted idea that TiO1.04 forms by quenching from high temperature.