In-situ investigation via high energy X-ray diffraction of stress-induced(0002)α→(110)β transformation in a Ti-5.5Mo-7.2Al-4.5Zr-2.6Sn-2.1Cr alloy

Abstract

The deformation and load partitioning mechanisms among phases are critical to the detailed understanding of heterogeneous stress distributions at the submicron scale during the process of elastic-plastic transformation in dual-phase (α+β) titanium alloys. Therefore, in this work, a Ti-5.5Mo-7.2Al-4.5Zr-2.6Sn-2.1Cr titanium alloy was investigated via in-situ high energy X-ray diffraction. We examined the evolution of the lattice strain, peak intensity, and full width at half maximum under uniaxial tensile loading at room temperature. The results indicated that the stress-induced (0002)α→(110)β transformation can be preferentially initiated for lattice strains of 702 × 10−6–1500 × 10−6 and 592 × 10−6–1355 × 10−6 during the elastic loading stage of the {0002}α and {110}β reflections, respectively. In addition, various dog-bone-shaped specimens with interrupted strain amplitudes (0.3%, 3%, 5% and 8.5%) were characterized via transmission electron microscopy. The corresponding selected area electron diffraction pattern confirmed the occurrence of a (0002)α//(110)β Burgers orientation relationship when the alloy was subjected to a strain of ε = 0.3%. Furthermore, the results revealed that the anisotropic non-linear response of specific reflections (i.e., the (0002)α and (110)β reflections) will cause a phase transformation.