Ni23Cr18Mo superalloy is synthesized via microwave-assisted alumino-silicothermic reduction. Mixed powders of NiO, Cr2O3, MoO3, and different ratios of Al and Si are employed as the reactants. The thermodynamical considerations and chemical and microstructural characterization of the synthesized alloys were studied by Factsage™ software, induction coupled plasma, scanning electron microscopy equipped with energy-dispersive spectrometer, and X-ray diffraction. Thermodynamical calculations suggested that all the samples could be synthesized via combustion synthesis. Accordingly, the priority of the reduction of elements is Ni, Mo, and Cr, respectively. Results indicated that the NiCr2O4 complex is formed during the synthesis. The low activities of Ni and Cr in this compound have a negative effect on the recovery efficiency of these elements. Moreover, the lower recovery efficiency of Ni relative to Mo can be attributed to the lower melting point of MoO3 than NiO. However, results show that in the specimens with a reduction share of Al less than 20 pct, the synthesis does not occur due to the high-melting point and low-solid-state reactivity of Si. It was found that there is a dependency between Cr recovery and the presence of Al. With increasing the reduction share of Al from 40 to 100 pct, the recovery efficiency of Cr is enhanced by 3.3 times. Furthermore, excess Al significantly affects the recovery efficiency of Cr. However, adding excess Al to the precursors increases residual Si in the final alloy and encourages the formation of the Mo2Ni3Si intermetallic phase.

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