Grain Refining and Oxide Dispersion Strengthening of Pure Titanium

Abstract

  Titanium (Ti) alloys are applied to various products used in the aircraft, automotive and motor cycles industries due to their high specific strength. Ti-6Al-4V (Ti64) is one of the most general Ti alloys, and shows superior mechanical properties i.e. density of 4.43 g/cm³ and tensile strength over than 900 MPa. However, its application is limited because of a poor plastic formability and the expensive raw materials.
   In this study, Roll-Compaction (RCP) process was applied to fabricate high strength pure titanium composite reinforced with titanium oxides (TiO₂) by using cheap sponge Ti powders as input materials. RCP was effective to improve the mechanical responses by the grain refinement and the in-situ formation of TiO₂ dispersions of the matrix. RCPed powder was consolidated by using spark plasma sintering (SPS) process to serve a high density compact. Subsequently, hot extrusion process was applied to the sintered billet to prepare a full density rod specimen. The evaluation of their mechanical properties at room temperature showed high tensile strength of 640 MPa and good elongation of 17%.