Compatibility of reduced activation ferritic martensitic steel JLF-1 with liquid metals Li and Pb–17Li

The corrosion of reduced activation ferritic martensitic steel, JLF-1 (Fe–9Cr–2W–0.1C), in high-purity Li was quite small. However, carbon in the steel matrix was depleted by the immersion to the Li. The depletion caused the phase transformation of the steel surface in which the morphology of the steel surface changed to ferrite structure from initial martensite structure. The phase transformation degraded the mechanical property of the steel. However, the carbon depletion and the phase transformation of the steel were suppressed in carbon doped Li. The carbon in the steel was chemically stable and did not dissolve into the Li when the carbon potential in the Li was high. The concentration of nitrogen and oxygen must be kept as low as possible because the corrosion was larger when the concentration of oxygen or nitrogen in the Li was higher. The chemical reaction between the steel and the Li compounds of Li3N and Li2O was also investigated. The corrosion of the JLF-1 steel in Pb–17Li was summarized as the dissolution of Fe and Cr from the steel into the melt. The corrosion of the specimen with Er2O3 coating fabricated by metal organic decomposition process in the Li and the Pb–17Li was investigated. The coating was deformed, cracked and partially exfoliated in the liquid metals, though the oxide itself was chemically stable in the liquid breeders. The damage was probably made by the stress, which was generated by a large difference of the thermal expansion ratio between the solidified Li or Pb–17Li and the coating during a heat up and a cool down process of the corrosion test.