The effect of rhenium doping on the high-temperature oxidation resistance of the Ni-based Inconel 713C superalloy manufactured using selective laser melting

Abstract

In this study, we investigated the impact of rhenium doping on the oxidation resistance of the Ni-based Inconel 713C alloy at 1000 °C. A rhenium dopant was introduced into the Inconel 713C alloy powder using an alternative to the mechanical method, a wet chemical method based on the sol–gel process. The doped powder was consolidated by an additive method using the selective laser melting technique, which allowed the Inconel 713C:Re alloy to be obtained. The high-temperature behavior of the Inconel 713C:Re alloy was compared with the alloy without a rhenium dopant, manufactured by SLM, and with the Inconel 713C alloy in cast form. Differences in the microstructure and chemical composition of the oxide scale formed on the tested samples were observed. For the SLM-manufactured Inconel 713C alloy samples undoped and Re-doped, the oxidation process was controlled by the outward diffusion of elements like Ni, Cr, Al, and Ti with simultaneous inward diffusion of oxygen along columnar grain boundaries. Oxygen diffusion was facilitated by the columnar shape of the grains and by the defects in the form of pores and microcracks introduced during the additive manufacturing process. The rhenium dopant significantly reduced the growth of the oxide layer on the Inconel 713C alloy exposed to a temperature of 1000 °C. Based on the determined oxidation rate constants, it can be concluded that the Inconel 713C:Re alloy showed higher oxidation resistance at 1000 °C compared to the other tested samples.