Metallic alloys overview for dynamic lithium corrosion of diverter system structural materials based on liquid lithium

Liquid lithium application in diverter systems for fusion devices requires an understanding of the compatibility of liquid lithium with various structural materials. Taking into account that flowing liquid lithium is more aggressive in comparison with static liquid metal, this work is devoted to the consideration of one of the important aspects of compatibility, namely the corrosion of materials in flowing liquid lithium resulting in the change of mechanical properties of components. The Center for Plasma-Materials Interactions (CPMI) at the University of Illinois at Urbana-Champaign (UIUC) has built an experimental instrument for testing the dynamic lithium corrosion of materials under lithium conditions, simulating the effect of liquid metal flow on a material by rotating at a controlled frequency of test samples in a volume of liquid lithium. All materials were exposed to lithium at 300° C for 100 hours at a rotational speed of 30 Hz. The level of corrosion of the samples was determined by assessing the changes in the mass of the samples, their surface characteristics (determined using 3D profilometry), as well as strength characteristics, which were measured using tensile tests of the samples. The result of this work is an overview of the mechanical characteristics of a set of metal alloys from the point of view of their application as lithium-facing materials in fusion devices. As a example, for Grade 5 Titanuim alloy it was found that heating lowered the strength of the material and lithium further lowered the strength while young’s modulus was decreased by heating and further by lithium.