Phase transformation kinetics during continuous heating of $\alpha$+$\beta$ and metastable β titanium alloys

The progress of environmental as well as performance targets that must be guaranteed by the transportation sector is highly conditioned to the availability of materials that can offer structural weight savings and improve engine performance. Titanium alloys are key materials in this regard owing to their superior specific strength with respect to other structural alloys and excellent corrosion resistance up to ~ 500 °C. However, these alloys are still associated with high production costs, and therefore, advances in manufacturing optimization are necessary to further extent their implementation. Since the mechanical properties of titanium alloys are consequence of microstructural-based alloy design controlled by the phase transformation kinetics during heat treating, a correct understanding of these processes is required.This dissertation focuses in the continuous and univocal study of the phase transformation kinetics during linear heating of α+β and metastable β titanium alloys from room temperature to the β field. An initial bi-modal microstructure is used to analyse the evolution of stable phases, namely α and β for the first group of alloys. On the other hand, decomposition of the β-quenched condition leading to formation of metastable products such as αʺ, ω and βʹ+β is studied for the second group of alloys. The investigations are carried out combining laboratory characterization methods with advanced synchrotron-based techniques including in situ high energy X-ray diffraction and micro X-ray fluorescence. Variations in the phase transformation sequences are presented as a function of heating rate. Furthermore, the continuous evolution of the crystal structure of phases is analysed in terms of the physical mechanisms involved during phase transformation