Comparative Hot Workability Characteristics of an Al–Si/SiCp Aluminium Matrix Composite Hybrid Reinforced with Various TiB₂ Additions

Hot compression tests were conducted on Al–Si/SiCp + TiB₂ hybrid aluminium matrix composites with various TiB₂ contents at temperatures from 350 to 500 °C and strain rates from 0.001 to 1 s⁻¹. The hot workability characteristics and deformation mechanisms were investigated by combining constitutive equations, processing maps and microstructural observations through scanning electron microscopy and transmission electron microscopy measurements. The results showed that there were small differences in the peak stresses when the contents of TiB₂ were 3% and 5%, while the peak stress increased when the content of TiB₂ reached 8%. The contents of TiB₂ had little influence on the activation energy but affected the processing maps to a certain extent. The areas of the instability zones were observed to gradually increase with increased TiB₂ additions. The optimal deformation conditions of the studied materials migrated from a low temperature and high strain rate to a high temperature and low strain rate with increasing TiB₂ content. In addition, the flow softening mechanism transformed from dynamic recrystallization + dynamic recovery to dynamic recovery with increasing TiB₂ content.