Das Korrosionsverhalten der Nickelbasislegierung Inconel 625

The corrosion behaviour of the nickel-based alloy Inconel 625 Due to its high resistance to corrosion by reactor coolants, water vapour and liquid sodium, the new high-temperature resistant nickel alloy Inconel 625 is well suited as fuel cladding material for a reactor of high energy density. Up to above 800° C, the scaling resistance in air is good. In electrolyte solutions, the general corrosion under conditions where a passivation layer cannot be formed or maintained is relatively slow. In accordance with expectations, Inconel 625 is not subject to intercrystalline corrosion by Strauss solutions even in the thermally sensitized condition, and even the reaction with nitric acid containing Cr^VI ions is not so much intergranular but superficial. If the material, together with V2A steel, is in contact with liquid sodium of 600° C, it is prone to chemical mass transfer. As a result, there occur precipitations of a new crystalline phase at the grain boundaries of the the Inconel 625 surface.