SIMS ANALYSIS OF OXIDE-FILMS FORMED ON FE -20CR-5AL ALLOYS

A charge neutralization method in SIMS was successfully applied to the analysis of La, Fe and Cr in Al2O3 films formed on Fe-20Cr-5Al alloy. The method consists of the preevaporation of Al or Au on the surface of the specimen except for the masked region and simultaneous irradiat ion of electrons. The surface charge was compensated for by the electr on irradiation. The pre-evaporated film served as the surface charge p ath. Elemental depth profiles of the oxide films on annealed and as-ro lled Fe-20Cr-5Al alloys showed that Fe and Cr were enriched in the sur face region, the Fe concentration in the former being lower than that in the latter. La and Al were also enriched in the surface region on a nnealed specimens before oxidation. These results suggest that the dif fusion of O during high temperature oxidation is retarded by the surfa ce oxide film on annealed specimens, and consequently resistance to hi gh temperature oxidation was improved.