Microtexture and nanoindentation of α and β phases in Ti-6Al-1.5Cr-2.5Mo-0.5Fe-0.3Si titanium alloy

Microstructure and nanoindentation of two-phase Ti-6Al-1.5Cr-2.5Mo-0.5Fe-0.3Si titanium alloy fabricated by drawing and subsequent annealing are systematically investigated. We find a strong fiber texture for α phase formed during drawing, which is characterized by crystallographic direction of 〈0110〉 parallel to the drawing direction, yet a weak texture for β phase, which is mainly consisted of 〈112〉 and 〈102〉 aligned with the drawing direction. The major texture components for the both phases during recrystallization are similar to those of the drawn state, but the corresponding texture intensities increase. A large number of α grains maintain the Burgers relationship with the β grains for the drawn and annealed states. In the case of the annealed specimen, the mean values of hardness and elastic modulus for α phase are found to be 5.79 GPa and 165.22 GPa, respectively, yet are 4.73 GPa and 152.06 GPa, respectively, for the β phase. Moreover, we also discuss the relation between elemental distribution and nanoindentation for individual phases. The hardness of textured α grains undergoes significant change as a function of the crystal orientation, in good agreement with the Schmid factor analysis. In contrast to the hardness, the measured elastic modulus values of α phase are less sensitive to the crystal orientation. No obvious change is identified for hardness and elastic modulus for β grains in that all the β grains are prone to generate slips.