Aluminum alloy (AA5083) is widely used in the aerospace and marine industries. However, its use is sometimes limited by its low surface hardness, wear resistance, and thermal stability. The microstructural, mechanical, tribological, and dynamic behavior of AA5083 matrix composites incorporated with mono-reinforcements (hexagonal boron nitride (hBN), graphene (G), and carbon nanotubes (CNTs)) and hybrid reinforcements (hBN+CNTs, G+hBN, and CNTs+G) by friction stir processing (FSP) is thoroughly investigated. Microstructural examination demonstrated that extensive dynamic recrystallization was induced by FSP, reducing the base-metal grains (about 215 μm) to very small sizes. The hybrid hBN+CNT composite had the smallest grain size (about 4.5 μm), the mono-CNT composite had the highest microhardness (~60 HV), whereas the hybrid CNTs+G composite had the highest ultimate compressive strength (~350 MPa). This enhancement was attributed to the formation of a 3D network within the hybrid composite, which hindered graphene agglomeration and restacking. Tribological tests revealed that hybridization greatly reduced wear; in particular, hBN-containing hybrids (hBN+CNTs and hBN+G) had the lowest wear rates (~0.037 mg/bar.min), owing to hBN’s solid-lubrication effect. Moreover, dynamic mechanical analysis and free-vibration testing showed the tunability of vibrational characteristics; the mono-CNT composite had the greatest structural stiffness (storage modulus ~72.75 GPa), whereas the G+CNTs hybrid had the best damping ratio (damping ratio ~4.82%). These results demonstrate that hybrid nanoreinforcements can tailor the multifunctional characteristics of AA5083 composites.
Alfahmi et al. (Thu,) studied this question.