Initial oxidation kinetics of FeNi single crystals before and after ion bombardment

Auger electron spectroscopy has been used to study the oxygen chemisorption kinetics on the (110), (100), and (111) faces of Fe + 36 at% Ni single crystal before and after bombardment with 5 keV argon ions to doses of 1015–1017 cm−2. The samples were exposed in O2 in a range up to 5000 L at temperatures of 20–300°C. At room temperature the chemisorption kinetics for the unirradiated crystal depends on its orientation, but it becomes almost isotropic after high-dose ion bombardment. At 300°C, the anisotropy in O2 uptake on the irradiated crystals is restored. The rates of Ni segregation and Ar thermal desorption for the irradiated alloy are found to depend on crystal orientation. Ion bombardment enhances the oxidation of the crystal.