Atom Probe Tomography of the Metal-oxide-interface in NiAlCr-alloys

Atom probe tomography (APT) permits to analyze interfaces in three dimensions with nearly atomic resolution. Recent development of the technique allows for analysis of oxides due to the application of short laser pulses, which tear ion by ion from the specimen surface. Due to this development, investigations of the metal-oxide interfaces became possible. Here we report about APT investigations of NiAlCr-alloys with additions of B, Ti, Y, Hf. The materials have been isothermally oxidized in dry air at 1100 °C for 100 h. APT analyses allowed to quantify segregation of Y and Hf at the metal-oxide interface and to exclude a significant presence of Ti and B. Furthermore, APT revealed the metal-oxide interface for the B containing alloy to be much rougher than initial transmission electron microscopy (TEM) suggested. This encouraged a more detailed look with high resolution TEM. Together these techniques allow a more detailed understanding of the oxidation process.