Indirect detection of grain-boundary segregation of carbon in iron-chromium alloys (Cr 10%) by electrochemical study

The electrochemical behaviour of ferritic iron-chromium alloys is strongly dependent on the quantity (even in trace amounts), the localization in the microstructure and the chemical state of impurities. By comparing the direct and reverse anodic curves of alloys with different microstructures, it is possible to distinguish the respective influences of carbon segregation and carbide precipitation on the formation and the destruction of passive film. Reciprocally, in some cases, the anodic curves can be used to detect micro segregations at grain boundaries whereas no microanalysis can yet achieve this. This possibility is very interesting because many properties of alloys are largely determined by the presence of grain-boundary segregation without precipitation.