Flow behavior and microstructure evolution of a TiBw/TA15 composite with network-distributed reinforcements during interrupted hot compression

Abstract

Interrupted hot compression tests were performed on a TiBw/TA15 composite with network architecture to study its flow behavior and microstructure evolution during a two-step deformation process. The microstructure was observed by electron backscatter diffraction (EBSD) and the high-temperature β grain boundaries were reconstructed through several special misorientation angles. The fraction of the primary α (αp) phase declined during the heat preservation process. The flow stress exhibited a lower value due to softening upon reloading compared to that observed prior to the interruption. In addition, the hold time and deformation temperature were important factors influencing the composition of the matrix phase, and the αp phase disappeared with increasing hold time and temperature. The high-temperature β grains became longer with a larger average aspect ratio when the deformation temperature reached 1283 K. Both TiB reinforcement and the αp phase restrained the growth of β grains, preventing hot deformation at higher temperatures and resulting in longer inter-pass holding times due to the absence of the αp phase. The low strain rates resulted in a significant β phase grain growth because of sufficient time and the lack of constraints. The optimized process parameters, which can provide guidance to actual production, were obtained in this study.