Thermal Expansion of Al Matrix Composites Reinforced with Hybrid Micro-/nano-sized Al₂O₃ Particles

The thermal expansion behavior of aluminum matrix composites reinforced with hybrid (nanometer and micrometer) Al₂O₃ particles was measured between 100 and 600°C and compared to theoretical models. The results revealed that the nanoparticle concentration had significant effect on the thermal expansion behavior of the composites. For the composites with lower nanoparticle concentration, their coefficient of thermal expansion (CTE) is determined by a stress relaxation process. While for the composites with higher nanoparticle concentration, their CTE is determined by a percolation process.