Topologically Ordered Corrosion Maps of Nickel Alloys

Abstract

This study was developed to provide an optimum methodology for designing metal alloys. Information on general and localized (pitting and crevices) corrosion of the most commonly used Nickel alloys were obtained from NIST. A 2-dimentional Kohonen map was designed and trained with the available data. We constructed a 3D figure (2D Kohonen map and a third dimension containing the corrosion rates of each cell in the Kohonen map) for all alloy-environment couples in the data. Once the Kohonen map was trained, we "designed" new Nickel-alloys by choosing two of the alloys (C22 and Incoloy 825 (UNS: N008825, alloy 825)) on the Nickel NIST list (composition, environment and corrosion rates), and by systematically modifying the alloy compositions by adding minor alloy elements (one at a time). For the newly created alloy, we chose the same environment as that of the original alloys (C22 or Incoloy 825). We located-in the Kohonen map-- the cells in which the original alloys (C22 and Incoloy 825) were stored; then, we located in which cells the "new alloys" are clustered. The alloys may migrate towards higher or lower corrosion rate cells. Accordingly, the beneficial or detrimental impact of adding those minor alloy elements in the alloys of origin (C22 or Incoloy 825) can be explored. Thereby, the "evolutionary road" of corrosion properties of metal alloys can be traced in the 3D figure and "If-then" scenarios for the new alloys - can be explored.