Precision Control of Oxygen Content in Cp-Ti for Ultra-High Strength Through Titanium Oxide Decomposition: An In-Situ Study

Oxygen has been known as an effective strengthening element in titanium alloys. However, an over-dose of oxygen can also lead to embrittlement of Ti alloys. To precisely control and push the limit of oxygen in Ti and its alloys, here we studied the decomposition process of Ti oxides in pure α-Ti matrix using an in-situ high-temperature scanning electron microscope (SEM), and evaluated the effectiveness of controlling oxygen content by using Ti oxide decomposition. The experimental results revealed that the TiO particles decomposed in α-Ti at elevated temperatures and the oxygen atoms gradually diffuse into the matrix, following the Fick’s second law. Then, CP-Ti samples of containing different oxygen contents were produced using the aforementioned strategy, for which the oxygen content, microstructure, and mechanical properties were measured. The results revealed that the oxygen content can be precisely controlled by the strategy. By following the Labusch law of strength prediction, an ultra-high-strength of nearly 1000 MPa was obtained with doping 0.87 wt.% oxygen in CP-Ti, at no expense of elongation-to-failure.