Effect of dispersion parameters and cold deformation on recrystallisation of Al–SiC composites

Abstract

AbstractThe effect of SiC whisker concentration (1–4 vol.-%), Al2O3 fine particle size and concentration (f/r=0·25–0·5 μm−1f volume concentrationr radius of particles), and degree of deformation by cold rolling (50–90%) on the recrystallisation behaviour and grain size in Al–SiC composites was studied. The result is of general interest as the Al–Al2O3–SiC composite is an alloy system with stable coarse and fine particles, the parameters of which can be varied independently over a wide range. The microstructure in the cold rolled state and initial stages of recrystallisation was examined using transmission electron microscopy. The recrystallisation temperature in different composites was determined by microhardness measurement after an isochronal heat treatment. The average grain size and grain size distribution in fully recrystallised composites were measured. It was found that the SiC whiskers act as strong nucleation sites and also enhance dynamic recovery, whereas the Al2O3 fine particles have the oppo...