Comparative evaluation of thermal and mechanical properties of nickel alloy 718 prepared using selective laser melting, spark plasma sintering, and casting methods

In this study, three different methods, namely, selective laser melting (SLM), spark plasma sintering (SPS), and casting techniques, were utilized to fabricate nickel alloy 718 samples. The effects of the fabrication methods on the mechanical and thermal properties of the samples were evaluated and correlated to the developed microstructure. All three methods produced samples with dense microstructure and high structural integrity. The choice of the fabrication method significantly affected the properties of nickel alloy 718. The SLM process provided highly compacted samples with high hardness values compared with those offered by the other two techniques. However, the SPSed sample fabricated at 1000 °C showed a higher thermal expansion (13.9 ppm K-1) than did the SLM and cast samples. The SPS temperature of 1000 °C was found to be optimum as a decrease in the SPS temperature to 900 °C resulted in a considerable reduction in the density. Moreover, samples produced by melting at 1450 °C and cast sample showed the highest thermal conductivity (10.3 W/m·k) amongst the samples.