Corrosion of Refractory Alloys in Molten Lithium and Lithium Chloride

Several refractory materials have been considered over the years as containment material for lithium and lithium halides. Surface modified refractory metals are being extensively investigated for containment of reactive metals, radionuclides and their compounds. An overview of experimental observations and results of liquid lithium corrosion of selected engineering refractory materials are presented. The nature of the degradation and its mechanism has been explained. The influence of temperature, microstructure, stress, impurities and service time on the corrosion behavior for various refractory alloys have been discussed. Selection rules for materials of containment for liquid lithium and lithium compounds have been suggested. Recent experimental observations on the behavior of tantalum and niobium-based refractory metal alloys in a specific molten salt environment comprising LiCl/Li₂O/Li/Li₃N at 725°C have been included in an effort to select suitable materials for molten salt equipment. It has been observed that oxygen contamination is particularly harmful for the refractory metal alloys where as nitrogen is deleterious to iron-based alloys.