Study on the dynamic deformation behavior and microstructure evolution of Ti-5Al-2.5Sn utilized Quasi-In-Situ method

Abstract

In this paper, the microstructural evolution process and deformation mechanism of annealed Ti-5Al-2.5Sn alloy under a high strain rate of 2700 s⁻¹ were investigated by quasi-in-situ method. The main deformation mechanism is found to be dislocation slip in the strain range from 0 to 0.05, and about 96% of the whole grain is deformed by dislocation slip, and $\left\{1\overline{1}00\right\}<11\overline{2}0>$ prismatic slip dominates the plastic deformation. When the strain increased from 0.05 to 0.10, the original slip system continued to move, and 13% of the whole grain activates the new slip system. In the strain range from 0.10-0.20, the number of slip traces does not increase significantly, and the new slip system is difficult to be activated. In the whole deformation process, about 42% of whole the grain activates a variety of slip systems including $\left\{1\overline{1}00\right\}<11\overline{2}0>$ prismatic slip and $\left\{\overline{1}101\right\}<11\overline{2}0>$ pyramidal <a> slip which activated at the same time. Results show that $\left\{11\overline{2}1\right\}$ twin only appeared in a few grains in the whole observed region, indicating that twinning is not the dominant deformation mechanism of annealed Ti-5Al-2.5Sn alloy at a high strain rate.