Transient oxidation in Fe-Cr-Ni alloys: A Raman-scattering study
- Cite this article as:
- Renusch, D., Veal, B., Natesan, K. et al. Oxid Met (1996) 46: 365. doi:10.1007/BF01048636
Using Raman scattering we have investigated the oxidation, in air, of the Fe-Cr-Ni stainless steels Fe-25Cr-20Ni, Fe-25Cr-20Ni-3Zr, and Fe-24Cr-3Zr (wt.%) as a function of temperature in the range 300 to 1000°C. The Raman technique is very sensitive to, and provides a clear identification of, the oxides Fe2O3 and Cr2O3. However, the technique is insensitive to NiO, FeO, and does not give a clear identification of spinels. The Fe−Cr−Ni alloys form chromia scales at temperatures greater than ∼800°C. At lower oxidation temperatures, transient phases are observed. With a 1-h heat treatment at 300°C, we observe the formation of an unidentified scale; we speculate that it is either amorphous or consists of disordered spinel(s). Near 400°C we begin to observe hematite (Fe2O3). The intensity of the Fe2O3 signal increases with temperature to ∼600°C and then decreases, being largely replaced by the signal from Cr2O3. The thickness of the Cr2O3 scale increases with temperature up to ∼1000°C above which spallation becomes apparent. Spinel phases also apparently persist in the scale to 1000°C.