Microstructure and mechanical properties of Inconel-GNP reinforced composites: A parametric study on ball milling and spark plasma sintering

The choice of processing technique adopted can improve the quality and properties of a material. This study optimizes the high-energy ball milling and spark plasma sintering (SPS) processing parameters to improve the microstructure and mechanical properties of IN718-GNP composites. Inconel 718 is a promising candidate in the field of advanced structural and high-temperature applications. However, high-efficiency energy systems demand increasingly high strength for advanced structural applications. Therefore, significant efforts are underway to enhance the strength of these materials. Various ball milling times and routes (dry/solution ball milling) were examined, along with spark plasma sintering conditions (sintering temperature and sintering/dwell time). Optimal microstructure and mechanical properties were achieved with 6 hours of dry ball milling and SPS temperature of 1100 °C for a dwell time of 5 min. The microstructure of samples was characterized using XRD, FESEM, TEM, EDS, EBSD, and the mechanical properties were evaluated using Vickers indentation and uniaxial tensile testing. GNP-reinforced IN718 sample showcased enhanced hardness, yield strength, and ultimate tensile strength by ∼29%, ∼43%, and ∼8%, respectively, compared to pure IN718 alloy, owing to the grain refinement, dislocation strengthening, Orowan strengthening, and solid solution strengthening. These findings underscore the potential of processing IN718-based composites in structural applications, offering a practical solution for the increasing demand for high-strength materials in advanced structural applications.