Lead-based melts (Pb, Pb-Bi) are considered as candidate coolants and spallation neutron targets due to their excellent thermophysical and nuclear properties. However, the corrosion of structural materials remains a major issue. Oxide dispersion strengthened (ODS) ferritic/martensitic steels are considered for high temperature application for both fission and fusion reactor concepts. The oxidation/corrosion kinetics in a static oxygen-saturated Pb melt at temperature of 550°C as well as the morphology and composition of scales formed on ferritic/martensitic Fe-9Cr-1.5W and ferritic Fe-14Cr-1.5W ODS steels have been investigated. Both materials showed homogeneous multiple, dense scales that consisted of typical combination of Fe3O4 as outer sublayer and (Fe,Cr)3O4 as inner sublayer. A nonuniform growth of inner oxide sublayers into the metal matrix as well as a good adhesion to the metal substrate is observed. With the prolongation of exposure from 240 to 1000？h, observed scales grow from 35？μm to 45？μm for ODS Fe-9Cr steel and from 40？μm to 60？μm for ODS Fe-14Cr steel with the thinning rates of 0,22 and 0,31？mm/year correspondingly. The mechanism of scales formation is discussed. 1. Introduction Lead-based melts (Pb, Pb-Bi) are considered for use in Generation IV reactor coolant and spallation neutron targets due to their excellent thermophysical and nuclear properties [1]. The advantage of lead as a nuclear coolant is derived from its physical and chemical properties [2]. At the same time, the corrosion aggressiveness of lead melts with regard to the structural materials is one of the main issues of up-to-date reactor material science [3]. To make this system usable at high temperatures (above 500°C), new classes of materials need to be developed and studied. Oxide dispersion strengthened (ODS) ferritic/martensitic steels are considered as candidate structure materials for high temperature application for both fission (Generation IV, Accelerator Driven Systems—ADS) and fusion reactor concepts [4, 5]. Their properties (high temperature strength and creep resistance) make them potentially usable for high temperature application in liquid metal cooled systems [6]. Although an application of ODS steels allows the working temperature limit to be increased up to about 700°C, it is known that the corrosion aggressiveness of liquid metals regarding steels strongly depends on temperature; that is, the higher the temperature, the larger corrosion losses [7, 8]. In addition to the temperature, the specific phase-structural state of ODS steels, that is, presence
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