Thermal gradient mass transfer in ferrous alloy Pb-17 at. % Li systems

Scanning electron microscopy and associated energy dispersive x-ray analysis of type 316 stainless and 12Cr-1MoVW steels exposed to thermally convective Pb-17 at. % Li yielded quantitative information about changes in surface morphology and composition as a result of mass transfer reactions. In the case of type 316 stainless steel, substantial preferential dissolution of nickel and chromium occurred at 5000C and led to the formation of a deep corrosion zone of irregular penetration. The extent and morphology of this corrosion zone was found to be sensitive to the starting microstructure of the steel. The 12Cr-1MoVW steel corroded uniformly with no change in its surface concentration. Mass transfer deposits in the type 316 stainless steel system differed depending on their position in the cold leg, where the temperature varied from 400 to 4600C. Depending on the temperature, the majority of the deposits were principally composed of iron, iron-nickel, or chromium. 3 refs., 8 figs., 1 tab