Preliminary Assessment of Spark Plasma Sintered Nickel-Based Quaternary Superalloy

In this work, the synthesis, characterization and mechanical properties of sintered In situ Ni-based quaternary superalloy (Ni–9Fe–22Cr–10Co) were studied. All the Ni–9Fe–22Cr–10Co quaternary alloy specimens were consolidated via spark plasma sintering technique at temperature range and sintering pressure of 850–1100 °C and 50 MPa, respectively. The densification of sintered alloys was obtained through Archimedes technique while the micro-indentation hardness of the alloys was conducted using Vickers microhardness tester. The specimens were characterized using the optical microscope and scanning electron microscope equipped with energy-dispersive spectroscopy while the phase identification was carried using X-ray diffractometer. The microstructural characterization results revealed that the relative density, surface morphology as well as the micro-indentation hardness properties depend on the sintering temperature. In addition, it was observed that high sintering temperature aided grain refinement and bulk compaction of the material leading to high relative density. XRD analysis shows the formation of Ni–Fe and Co–Fe as the major phases. Generally, the densification and grain size of the alloys increased with increasing sintering temperature with optimum results obtained at a temperature of 1100 °C and sintered density of 98% while the maximum Vickers hardness value of 439.17 HV₁ was recorded.