An Investigation into the Microstructural Response to Flexural Stresses of a Metastable β-Phase Ti Alloy produced by Blended Elemental Powder Metallurgy

A Ti-10V-3Al-3Fe metastable β Ti alloy is strained under three-point bending conditions according to the ASTM E290-14 standard. A combination of electron backscatter diffraction (EBSD) mapping and high-resolution scanning transmission electron microscopy (STEM) is used to investigate the microstructural response to flexural stress. Results reveal a delayed formation of the deformation products, due to the load-bearing capacity of the constituent voids. The deformation products are confined in narrow bands on either side of the fracture surface. {332}⟨113⟩ twinning system is identified as the primary deformation mode followed by the formation of α″ martensite both in β matrix and β twins. Accommodation of the microscopic strain arising from the development of α″ structure and β-twinning triggers the formation of fine deformation-induced ω plates, which are observed predominantly at the interfacial plane of β/β twin and β/α″, and also in the interior of the β twins.