AFM analysis of duplex steel structure and composition

Due to the high content of alloying elements, duplex stainless steels are characterized by a complex structure of phase transitions. Among all types of intermetallic compounds, the sigma phase is of major interest due to its detrimental effect on both mechanical properties and corrosion behavior. It is an intermetallic phase enriched in Cr and Mo and therefore its formation impoverishes adjacent regions with the above components contributing to lowering the corrosion resistance of the described type of steel. Due to the measurable differences in the volt potential values, corresponding to austenite and ferrite as well as the σ phase, the scanning technique of the Kelvin probe seems to be adequate for the differentiation and qualitative identification of individual phases. The described collection contains 14 topographic and potential images showing the differentiation of the surface potential, correlated with the sample topography. [1]. N. Nonnenmacher, M.P. O’Boyle, H.K. Wickramasinghe, Kelvin probe force microscopy, Appl. Phys. Lett. 58 (1991) 2921. doi:10.1063/1.105227.