Tribo-mechanical performance of IN718 superalloy fabricated via casting, selective laser melting, and spark plasma sintering

Inconel 718 (IN718) is a high-performance nickel-based superalloy extensively utilized in critical applications; however, its tribological behavior under severe conditions continues to raise significant concerns. This study investigated the effects of various fabrication methods, including selective laser melting (SLM), spark plasma sintering (SPS), and cast samples, on the tribo-mechanical performance of the IN718 alloy under dry sliding conditions. A thorough analysis was performed via microstructural characterization, nanoindentation testing, and performance evaluation to establish correlations among processing techniques, microstructural evolution, and material performance. All three techniques yielded samples characterized by high densification (≥98 %) while maintaining structural integrity. Nevertheless, the SPS-fabricated samples demonstrated the highest elastic modulus (≈200 GPa), suggesting superior stiffness, attributable to their fine-grained, densely consolidated microstructure, along with a moderate hardness value of approximately 290 HV and enhanced wear resistance, indicated by the lowest specific wear rate (≈32.471 μm³/Nm) and a low coefficient of friction (COF ≈0.585). This outstanding performance is linked to their fine-grain structure, improved elastic modulus, and diminished porosity, resulting in greater resistance to plastic deformation and wear-induced material removal. These findings underscore the pivotal role of fabrication techniques in optimizing the tribological and mechanical performance of IN718 alloys, providing valuable insights for the advancement of high-performance components in demanding engineering applications.