Oxidation Resistance and Nanoscale Oxidation Mechanisms in Model Binary and Ternary Alloys Exposed to SCW

Abstract

Model binary and ternary steels were fabricated, containing 9% Cr and 1.5% (atomic) of one of a number of elements (Si, Al, V, Mn, Ti) that might be expected to influence SCW oxidation, using as a general guide the experience with such alloying elements in high-temperature gaseous oxidation. The results reveal a promising effect of alloyed Si on oxidation resistance, although some intergranularity is evident ahead of the oxidation front. Nanoscale, clustered Si enrichment at the uniform oxidation front was revealed by high-resolution analytical electron microscopy of FIB sections, but the details are still under investigation. Internal oxidation of Cr (and/or Si) with various morphologies was also observed near the oxidation front.