Mechanical and high temperature wear properties of extruded Al composite reinforced with Al₁₃Fe₄ CMA nanoparticles

The mechanical and tribological properties of extruded aluminum matrix composites reinforced with various weight percentages (1, 3, 5, 7, 10wt.%) of Al₁₃Fe₄ complex metallic alloys (CMAs) were investigated. The nanocomposites were produced using conventional powder metallurgy and a hot extrusion process. The tribological behavior of the composites was investigated under normal loads in the range of 20-80N using a reciprocating high-temperature tribo-tester over a temperature range of 25-350°C. At an optimized reinforcing agent concentration of 5wt.%, the composite showed a significant enhancement in Young's modulus (~108MPa) and hardness (~1.85GPa). The lowest coefficient of friction of 0.1 was attained at a temperature of 250°C with a reinforcing agent concentration of 5wt.%. Also, the wear rate was reduced by a factor of ~25 compared to the unreinforced aluminum specimen. The significant improvement in the tribological properties of the nanocomposite was attributed to the enhanced mechanical properties due to severe plastic deformation incurred during the extrusion process and incorporation of well distributed CMA nanoparticles in the matrix which provided õobstacles for dislocation motion. Detailed microstructural analyses revealed that incorporation of the second phase to the Al matrix led to microstructure refinement and increased the hardness up to ~2GPa. Furthermore, the nanoparticles aided in the formation of hard and temperature-resistant tribo-layers which reduced the wear rate of the composite (Al-5wt.% Al₁₃Fe₄) down to 1.5×10^-4 at 250°C.