Carbon nanotube-reinforced intermetallic matrix composites: processing challenges, consolidation, and mechanical properties

Intermetallic compounds (NiAl) are potential high-temperature structure materials due to their exceptional physical and thermo-mechanical properties. NiAl offer a wide range of applications which stem from aerospace to automobile industry but their utilization is restricted owing to low ductility and fracture toughness. However, carbon nanotubes (CNTs) have been recognized to impact strength and improve mechanical properties in metal matrices because of their superior tensile strength, high aspect ratio, low density, and elastic modulus. This has contributed to advance developments of novel materials. In recent times, CNTs have been a focus of immense research due to presence of sp² C–C bonds in their outer shells, with continuous cylindrical shape which significantly contributed to their superior characteristics. The processing methods of integrating CNTs in metal matrices as well as maintaining their structural integrity through the powder metallurgy routes are reviewed. The mechanical properties, microstructure evolutions, effect of CNT addition, and sintering mechanism are also articulated in this review.