Corrosion of pre-oxidized nickel alloy X-750 in simulated BWR environment
Journal article, 2017

Samples of pre-oxidized Alloy X-750 were exposed to a simulated boiling water reactor environment in an autoclave at a temperature of 286 °C and a pressure of 80 bar for four weeks. The effect of alloy iron content on corrosion was investigated by comparing samples with 5 and 8 wt% Fe, respectively. In addition, the effect of two different surface pre-treatments was investigated. The microstructure of the formed oxide scales was studied using mainly electron microscopy. The results showed positive effects of an increased Fe content and of removing the deformed surface layer by pickling. After four weeks of exposure the oxide scale consists of oxides formed in three different ways. The oxide formed during pre-oxidization at 700 °C, mainly consisting of chromia, is partly still present. There is also an outer oxide consisting of NiFe2O4 crystals, reaching a maximum size of 3 ?m, which has formed by precipitation of dissolved metal ions. Finally, there is an inner nanocrystalline and porous oxide, with a metallic content reflecting the alloy composition, which has formed by corrosion. © 2017 Elsevier B.V.

STEM

Oxidation

SEM

TEM

Superalloys

Nickel

Author

Silvia Tuzi

Chalmers, Physics, Materials Microstructure

Haiping Lai

Chalmers, Physics, Materials Microstructure

Kenneth Göransson

Westinghouse Electric Sweden AB

Mattias Thuvander

Chalmers, Physics, Materials Microstructure

Krystyna Marta Stiller

Chalmers, Physics, Materials Microstructure

Journal of Nuclear Materials

0022-3115 (ISSN)

Vol. 486 1 April 350-360

Driving Forces

Sustainable development

Roots

Basic sciences

Subject Categories

Metallurgy and Metallic Materials

Areas of Advance

Materials Science

DOI

10.1016/j.jnucmat.2017.01.051

More information

Latest update

11/1/2018