ABSTRACT
A method for photolithographic deposition of inert markers of submicrometre dimensions onto metal substrates prior to oxidation is described. The fine scale of the marker deposition avoids the difficulties encountered with conventional markers, whose size may exceed that of those microstructural features controlling oxidation. Their regularity provides a more reliable demarcation of original interface postitions than do other irregularly-deposited markers. The new technique has been applied to the high-temperature oxidation of pure Ni, Ni-1at%Al and Ni-1at%Cr alloys. Observation of the markers using cross-sectional transmission electron microscopy (XTEM), scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) has revealed striking differences in the scale morphology, microstructures and oxidation mechanisms between pure Ni and the dilute alloys. In particular, the results suggest that small Al and Cr additions promote significant inward transport of oxygen. The presence of the markers appears to affect only marginally the oxidation kinetics and local oxide morphology.
