Effect of oxygen on Te infiltration into superalloy Inconel 718 at elevated temperature

Abstract The atmosphere for alloying element infiltration into bulk materials has important effects on the alteration of their original microstructure and mechanical properties. The present work studies the effect of nitrogen and air atmospheres on the process of tellurium (Te) infiltration into superalloy Inconel 718 at high temperature. The depth and microstructure of the infiltration layer present remarkably distinct phenomena in different atmospheres. Microstructure analysis were used to analyze the microstructure and element distribution within the infiltration layer. Nano indentation was performed to assess the mechanical properties of intercrystalline compounds and matrix. The results show that oxygen is the main factor for the promotion of Te infiltration process. At last, the mechanisms of the infiltration of Te into Inconel 718 in nitrogen and air atmospheres were explained. The clusters of oxides, formed at grain boundaries due to reaction between the oxygen and precipitates, lead to the weakening of grain boundaries and create a path for Te to enter the bulk material. This study can not only help to understand the influence of gas atmosphere on material properties during the Te infiltration process, but also has guiding significance to prevent material failure and design material compositions.