Hot deformation characteristics and mechanism of PM 8009Al/SiC particle reinforced composites

The hot deformation behavior of powder metallurgy-processed 8009Al alloys reinforced with 15% SiC particles (8009Al/SiCp composites) was investigated by compression testing at temperatures of 400–550°C and strain rates of 0.001–1s–1. The corresponding deformed microstructures were characterized by scanning and transmission electron microscopy. The results showed that the flow stress increased with increasing strain and then stabilized at a constant value after reaching a peak value. The stress level decreased with increasing deformation temperature and decreasing strain rate, which could be represented by a Zener-Hollomon parameter in the hyperbolic-sine equation that integrates strain, temperature and strain rate. The deformation activation energy for the 8009Al/SiCp composites was calculated to be 481–495kJ/mol. The flow behavior of the composites was attributed to intense dynamic recovery caused by the high volume fraction of very fine Al12(Fe,V)3Si-phase dispersoids in the Al matrix. The accommodation ability between the SiC particles and the Al matrix was discussed as well.