Processing and Characterization of Nickel Matrix Nanocomposites Reinforced with Layered Nickel Aluminide Intermetallics Using Mechanical Alloying and Spark Plasma Sintering

This research discusses the fabrication of a nickel matrix nanocomposite reinforced with in situ synthesized layered Ni₃Al intermetallics using mechanical alloying (MA) and spark plasma sintering (SPS). In contrast to ex situ methods that frequently produce weak interfaces, the in situ approach enhances bonding and mechanical performance by using layered Ni₃Al reinforcements with excellent deformation resistance and load-bearing potential. Twenty-hour milled Ni-Al powders were annealed at 700 °C and consolidated using SPS, achieving approximately 96% theoretical density. The nanocomposite showed exceptional mechanical properties, with a hardness of 350 ± 15 HV in contrast to 200 ± 5 HV for pure Ni, along with higher wear resistance and reduced wear track depth. These improvements resulted from microstructural refinement and the development of hard intermetallic phases. X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the formation of a homogeneous layered Ni₃Al structure inside the matrix, showing a crystallite size of around 40 nm post-milling. Layered reinforcements enhanced matrix–reinforcement interactions, thereby minimizing common challenges in traditional composites. This innovative production technique highlights the future potential of Ni₃Al-reinforced nanocomposites as high-performance materials for advanced engineering applications, combining outstanding mechanical and tribological properties with strong structural integrity.