PRODUCTION OF OXIDE DISPERSION STRENGTHENED INCONEL 718 ALLOYS USING CONVENTIONAL POWDER METALLURGY AND ADDITIVE MANUFACTURING METHODS

Abstract

Oxide dispersion strengthened (ODS) Ni-based alloys having a high density of nano-oxides (NOs) (<10 nm) are considered to be good candidates for extreme environments, such as high temperature, radiation, and corrosion. In this study, ODS IN718 alloys have been produced using conventional powder metallurgy (PM) and novel selective laser melting (SLM) additive manufacturing. The effect of processing routes on the microstructure, in particular on the nano-oxide formation and structure has been investigated. It has been found that the powder metallurgy method that consists of compressing followed by sintering at 1250 and 1500 °C results in a nano-granular structure with homogenously distributed fine nano-oxides having a high number density. Similarly, SLM results in a high number density of fine nano-oxides; however, the particles exist in groups with the grains/cells. The nano-oxides are determined to be Y2Ti2O7, Y2TiO5 or YTiO3 and Y-Al-O. The deviation in the lattice parameters of Y2Ti2O7 infers the existence of some Al in the structure. This study sheds light on producing ODS IN718 alloys with high-density nano-oxides using powder metallurgy and additive manufacturing methods.