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

Abstract

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.