Effects of TiB2 particles on deformation behavior, softening mechanisms and recrystallization texture of hot-compressed Fe-TiB2 composites

Abstract

Fe-TiB₂ composites, also termed as high modulus steel, offer a promising solution to the challenge of achieving both lightweight and high stiffness materials. However, the presence of TiB₂ particles in Fe-TiB₂ composites results in poor hot-workability. Therefore, understanding the effects of TiB₂ particles on the hot deformation behavior, dynamic recrystallization (DRX), and microstructural evolution of Fe-TiB₂ composites is crucial for optimizing their hot-working process. In this study, we elucidated the effects of TiB₂ particles on deformation behavior and dynamic softening behavior by conducting a series of isothermal compression tests on as-cast Fe-TiB₂ composites and as-cast base alloys (control group) at temperatures of 800–1200 °C, strains of 0.36–1.2, and strain rates of 0.01–1 s⁻¹. Using electron backscatter diffraction, we characterized the microstructures of composites and base alloys, showing that TiB₂ particles induce a DRX process through particle stimulated nucleation (PSN) at low temperatures and promote continuous dynamic recrystallization (CDRX) at high temperatures. The presence of TiB₂ particles have significantly affected the dislocation movement and distribution, which changes the deformation energy distribution and thus facilitates different DRX behaviors under various thermal deformation conditions. Additionally, the microstructure resulting from DRX through PSN exhibits significant texture weakening and grain refinement, presenting a promising method for fabricating ultrafine-grained Fe-TiB₂ composites.