Measuring Oxygen Solubility in Ni Grains and Boundaries after Oxidation Using Atom Probe Tomography

Abstract

Poor oxidation resistance is a key contributor to material failure within extreme environments. Understanding oxygen solubility is important for computation aided design of new high strength, high-temperature oxidation resistant alloys. Oxygen solubility within pure metals, such as Ni, has been studied using a multitude of techniques, but Atom Probe Tomography (APT) has not been used for such a measurement to date. APT is the only technique offering both a high chemical sensitivity (<10 ppm) and resolution (<1 nm) allowing for a composition measurement within nms of the oxide/metal interface. APT was employed to measure the oxygen content at different depths from the oxide/metal interface as well as grain boundaries for a high and low purity Ni sample oxidized at 1000 °C for 48 hours. The results reveal <10s of ppm oxygen solubility within Ni metal at all depths and 100s of ppm of oxygen within GBs.