Heat treatment effects on microstructure and tensile response of TA15 near-alpha titanium alloy

This research examines the arrangement of microstructures and the localized deformation patterns in a heat-treated, TA15 near-alpha titanium alloy produced via laser melting deposition, under tensile stress, employing in situ scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) for detailed analysis. At the microscopic level, three distinct microstructures can be identified: at 750 °C, a single-phase α matrix exhibiting a basketweave pattern; at 950 °C, fine α precipitates dispersed within a transformed β matrix; and at 1050 °C, a fully lamellar α+β structure. These three distinct microstructural samples exhibited different mechanical responses under tensile loading conditions. KAM and band contrast analyses show stress accommodation evolving from uniform slip in HT1 to widespread plasticity in HT2, then stress concentrating at β-boundaries in HT3, revealing distinct dislocation behaviors. Pole figures show HT1’s texture weakens and rotates under stress, HT2’s grains align directionally, while HT3’s stable texture resists change due to its coarsened lamellar α + β microstructure.