In situ oxidation, experiments were carried out using 3mm diameter discs with one surface ground and polished to a 1μm diamond finish. The 3mm discs were then oxidised in a Philips XL-30 FEG ESEM with a hot stage attachment. The oxidising atmosphere used was laboratory air at a pressure of 266Pa. During the experiment, the sample was observed and imaged using a primary beam energy of 20kV and an Everhart–Thornley secondary electron detector. The sample was heated at a rate of 100°C/min to a temperature of 700°C and held at this temperature for 8min to stabilise the stage and the microscope. The sample was then heated to a final temperature of 900°C at the same heating rate. The total time of exposure of the sample was 120min before cooling to room temperature by turning off the heating coils. The samples were then examined in the LEO 1530VP FEGSEM with chemical information gathered using EDS. Cross-sections and Transmission Electron Microscope (TEM) samples were produced using a dual beam FEI Nova Nanolab 600 for Focused Ion Beam (FIB) milling perpendicular to the phase boundaries to determine their influence on the oxide development and imaged using a Jeol 2000FX W-filament TEM. EDS maps of the TEM samples were collected using the Nanolab 600 with a Scanning TEM (STEM) detector and an EDAX Genesis EDS system at an accelerating voltage of 30kV.
