Microstructure evolution of TiBw/Ti composites during severe plastic deformation: Spheroidization behavior

In this study, 2.5 vol% TiBw/Ti composites were subjected to isothermal multi-directional forging (IMDF) at 1020 degrees C with various strain rates, aimed to investigate the spheroidization behavior of TiBw /Ti composites with initial widmanstatten microstructure. It is found that strain rate has a significant effect on the spheroidization of microstructure. Dynamic recovery (DRV) of alpha phase occurs at high strain rate while dynamic recrystallization (DRX) dominates microstructure spheroidization with the decreasing of strain rate. It is worth noting that alpha lamella and alpha colony exhibit different spheroidization behavior, which leads to the heterogeneity of microstructure. Moreover, the relationship between crystallographic orientation and imposed strain play an important role in the spheroidization process. The schmid factor calculated by EBSD was used to identify and predict heterogeneous deformation phenomena of alpha colony. The spheroidization process can be promoted by TiB whiskers due to the introduction of large deformation in the matrix.

Automated summary

This study investigated the spheroidization behavior of TiBw/Ti composites subjected to isothermal multi-directional forging with different strain rates. The results showed that strain rate significantly influenced the microstructure spheroidization process, with dynamic recovery at high strain rates and dynamic recrystallization dominating at lower strain rates. Additionally, the relationship between crystallographic orientation and imposed strain played a key role in the spheroidization process, indicating the importance of heterogeneous deformation phenomena in the alpha colony.