Fig. 5

APT compositional analysis of the oxide/alloy interface shown in Fig. 4. a–b Iso-composition surfaces of a region in the alloy immediately below the oxide layer. These surfaces define regions that contain > 55 at% Ni and > 21 at% (Al + O). c A one-dimensional profile taken through the inward-growing oxide and the adjacent low-density regions. The profile shows the detected total number of atoms and the number of Ni, O, Al, and Cr atoms as a function of distance in the volume defined by the 3-nm diameter cylinder (a 1-nm bin width was used). Error bars represent the square root of the number of detected atoms