It is clear from Fig. 3 that the Fe 2p spectra show similar
shapes and intensities during prolonged sputtering. Moreover,
after a 20-min ion bombardment, a metal component
appears in the Fe 2p spectrum. It cannot be attributed to
ion-induced reduction of iron oxide to metal, because no
such data are to be found in the literature. We suppose that
the Fe0 signal originates from parts of the crevices, accessible
to ion bombardment where the sputtering eliminates
the thin oxide film, thus revealing the underlying steel surface.
On the other hand, both chromium and oxygen signal