The Effect of Rolling Conditions on the Properties of Aluminum Powder Composites Reinforced by Sic, Tic, and AIB12 Nanoparticles

The effect of high-temperature deformation conditions on the mechanical properties of composites produced from aluminum powders with different particle sizes reinforced by SiC, TiC, and AlB12 nanoparticles was examined. High-temperature extrusion promoted uniform distribution of the nanoparticles in the aluminum matrix. At an optimum nanoparticle content (4 wt.%), the most uniform distribution of particles following deformation was shown by the composites produced from a fine size fraction of the aluminum powder. Subsequent high-temperature rolling promoted significant strain hardening (up to 120 MPa) through thermokinetic deformation conditions giving rise to dislocation substructures and activating dynamic recrystallization processes. In all cases, the hardening rate at the initial stage of high-temperature rolling (first pass) was higher than at the subsequent stages when recovery processes activated. The abnormal decrease in strength of the samples subjected to asymmetric rolling to reach high strains was associated with intensification of shear deformation, increasing the ribbon internal energy and thus accelerating the annealing of deformation defects. Among the nanopowder reinforcements, the best mechanical behavior was demonstrated by SiC nanoparticles, whose structural features promoted the best bonding between the particles and the matrix. The samples with AlB12 nanoparticles showed lower hardening because of somewhat weaker bonding and process-induced particles. Titanium carbide nanoparticles provided the worst hardening of the composite because of insufficient bonding with the matrix. The tested deformation conditions, along with the optimal choice of powder components for the composites, allow the production of high-strength ribbons (aluminum metal-matrix composites) employing a relatively simple powder technique. A further increase in the ribbon strength should be promoted by the use of doped aluminum powders following upgrade of the deformation conditions.