Effects of carbon nanotube weight fraction on the fracture toughness of spark plasma sintered nickel aluminide-NiAl₃

Nickel aluminides have captured the attention of researchers for a few years now owing to their lightweight and high strength. They possess a huge potential for high temperature applications primarily due to their structural integrity at elevated temperatures. However the major limiting factor of these promising intermetallics is their room temperature fracture toughness, which is too low to satisfy service requirements. Although there are majorly three groups of nickel aluminides NiAl, Ni₃Al and NiAl₃, only the NiAl and Ni₃Al groups have been intensely researched while documented literature on NiAl₃ is rare, despite being the lightest intermetallic in the group. In this work, carbon nanotubes were incorporated into NiAl₃ and consolidated using the spark plasma sintering (SPS) technique. The effect of carbon nanotube (CNTs) reinforcement on the fracture toughness of NiAl₃ was studied. It was observed that the addition of the carbon nanotubes improved the fracture toughness of the reinforced composites over the un-reinforced sample initially, but the fracture toughness reduced with increase in carbon nanotube weight fraction.