The corrosion properties of Ni-Cr-Mo-Gd alloys that are being developed for use as a neutron-absorbing structural material were examined. The corrosion work was part of a larger alloy development program. The corrosion properties were examined by both electrochemical and longer-term immersion testing in standard test solutions and in simulated solutions used in corrosion testing by the Yucca Mountain Project. The addition of Gd to a Ni-Cr-Mo alloy results in the formation of a gadolinide (Ni5Gd) secondary phase. This phase was observed to preferentially dissolve under electrochemical testing at anodic potentials. The reaction appears to be mostly limited to the secondary phase exposed to the surface. A brief comparison with another neutron-absorbing alloy, borated stainless steel, is made.

Subject
Scanning electron microscopy, Electric current, Test methods, Water, Materials, Composition, Stainless alloys, Corrosion rate, Nickel based alloys, Molybdenum alloys, Nickel chromium molybdenum alloys, Sodium chloride solution, Heat
Keywords:
alloy composition, corrosion rate, gadolinium, localized corrosion, neutron-absorbing material, nickel-based alloy, temperature, Yucca Mountain Repository
NACE International
2005
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