A Study on Deformation Mechanisms of Ti2AlNb-Based Alloy Under Plane Strain Compression

As a superalloy, Ti2AlNb-based alloy faces a great challenge due to the commonly existent centimeter-level coarse grains in as-cast material, which severely deteriorate their mechanical property. In-depth understanding of plastic deformation heterogeneity at grain-level of this material is pivotal in exploring the nucleation mechanism of recrystallization. In-situ plane compression tests combined with surface slip line observation and microstructure tracing were carried out on samples with centimeter-grade coarse grains. The results showed that the plastic deformation was heterogeneous in the samples, and the grain boundaries had little effect on hindering dislocation movement. Macroscopic shear direction significantly influenced the distribution of slip lines. Slip can be transferred from one grain to the neighbor grains through the grain boundary without changing the direction. Surface slip trace analysis showed that only a few slip systems were activated in grains. The activated slip systems in grains were affected by the orientation of the surrounding grains. The high deformation stored energy was formed at the band structure and the grain boundaries, and these regions can further occur recrystallization by aid of the heat effect.