Microstructure and Mechanical Properties of Spark Plasma-Sintered Graphene-Reinforced Inconel 738 Low Carbon Superalloy

The effects of the addition of different percentage compositions of graphene nanoplatelets (GNPs) to a nickel-based superalloy were investigated in this study. A spark plasma sintering (SPS) method was employed in the development of the nickel-based alloy/composites, and the developed bulk nickel-based alloy and its composites were from high-purity micron-size powder. Subsequently, the microstructure and mechanical properties (i.e., microhardness and tensile yield strength) were examined. The SPS-processed nickel-based alloy/composite samples exhibited high densification ranging from 97.64 to 98.87 pct. The addition of GNPs greatly influenced the microhardness results, which ranged from 384 to 459 Hv, and the tensile yield strength between 675 and 883 MPa. The results indicated that the addition of graphene nanoplatelets played a significant role in the microstructure and mechanical properties of spark plasma-sintered nickel-based composites. The addition of graphene nanoplatelets caused grain boundary strengthening, load transfer from the matrix to GNPs, and grain boundary strengthening by impeding dislocation movement. Coupled with the improvement caused by GNPs is the enhancement of the mechanical properties of the materials developed as a result of the high relative density values obtained.