Unexpected accelerated corrosion of Cr in Ni-xW-6Cr alloy with W content increasing

The influence of W content upon corrosion of Ni-xW-6Cr alloys in molten FLiNaK salts at 850 °C was examined. The results indicate a significantly greater depletion of Cr and W from Ni-xW-6Cr alloys with higher W contents in the molten FLiNaK salt, which mainly results from the increasing activities of W and Cr in the alloy with the W content increasing. The high concentrations of oxygen, Ni and Fe impurities further accelerate the corrosion of W and Cr from the alloy by providing more corrosion vacancies as diffusion paths in the alloy's near surface area.