Microstructural Evolution and Deformation Behavior of a Solution-Treated Ti-Al-Mo-Fe Metastable Beta Titanium Alloy during Room-Temperature Deformation

Abstract

Beta titanium (β-Ti) alloys have been widely used in aerospace and biomedical implants due to their specific strengths, low elastic modulus, and their resistance to corrosion. As β titanium alloy is a novel metastable, Ti-2Al-9.2Mo-2Fe (wt.%) alloy is essential to understand microstructural evolution and deformation behavior at room temperature to improve the strength–ductility balance. The deformation behavior and microstructural evolution of the Ti-2Al-9.2Mo-2Fe alloy during room-temperature deformation has been investigated via electron backscatter diffraction (EBSD) and electron channeling contrast imaging (ECCI). It was found that the β-solution-treated alloy exhibited a single β phase with a lower β stability. However, the α/β-solution-treated alloy exhibited a layered structure, consisting of fine α + β grain layers and coarse β grain layers, and the β in the coarse grain layer had a lower stability, but the β in the fine grain layer had a higher stability owing to the coexistence of α. The β-solution-treated alloy was mainly deformed via {332} deformation twinning, thus showing very high ductility; uniform elongation of approximately 35%. The α/β-solution-treated alloy was deformed via two mechanisms, namely {332} deformation twinning in the coarse grain layers and dislocation slip in the fine grain layers. The α/β-solution-treated alloy exhibited high strength with a lower ductility due to the small amount of deformation twinning.

Keywords

• β titanium
• deformation behavior
• TWIP
• EBSD
• ECCI