Corrosion and combined radiation/ corrosion effects on Ni-Mo-Cr-Fe alloy GH3535. Rohan L. Holmes 1 , Hanliang Zhu 1 , Tim Palmer 1 , Inna Karatchevtseva 1 , E.R. Vance 1 , Daniel Gregg 1 , and Tracey Hanley 1 . 1 The Australian Nuclear Science and Technology Organisation, Locked Bag 2001,Kirrawee DC, Sydney, NSW, 2232, Australia [email protected] Molten salts have a number of industrial applications ranging from aluminum refining to heat-transfer media in solar-thermal plants and nuclear applications. For molten salt cooled reactors employing fluoride based molten salts, a number of nickel based alloys offer reasonable resistance to fluoride corrosion. Recently, fluoride salt cooled reactors have returned to prominence due to their selection as one of the six generation IV reactor designs under consideration. For this reason, the aims of this work were to assess the corrosion of nickel-based alloys and investigate the combined effects of radiation damage and corrosion. In this work, the corrosion behavior of a nickel-based alloy (GH 3535, procured from the Shanghai Institute of Applied Physics) in LiF-NaF-KF molten salt was explored. The interaction of radiation damage and corrosion was also assessed by damaging the alloy surface using helium ions with energies up to 30keV at an ion fluence of 10 17 ions/cm 2 . Accelerated corrosion experiments were conducted at 750°C for times of 10, 100, and 200h with samples characterised using optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and positron annihilation lifetime spectroscopy. Intergranular attack was the main mode of corrosion observed for samples exposed only to molten salt. However, for helium ion damaged samples, corrosion resulted in a combination of intergranular and intragranular attack. From TEM, the size of the corrosion layer was found to be more than 30 fold larger for the helium ion damage/corroded sample compared with the corroded sample. The mechanistic effects of He ion irradiation on the corrosion of Ni alloys was also investigated. In addition, preferential salt attack towards

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Page 1: Abstract Template - Amazon Simple Storage Service (S3 ... · Web view... 100, and 200h with samples characterised using optical microscopy, scanning electron microscopy, transmission

Corrosion and combined radiation/ corrosion effects on Ni-Mo-Cr-Fe alloy GH3535.

Rohan L. Holmes1, Hanliang Zhu1, Tim Palmer1, Inna Karatchevtseva1, E.R. Vance1, Daniel Gregg1, and Tracey Hanley1.

1The Australian Nuclear Science and Technology Organisation, Locked Bag 2001,Kirrawee DC, Sydney, NSW, 2232, Australia

[email protected]

Molten salts have a number of industrial applications ranging from aluminum refining to heat-transfer media in solar-thermal plants and nuclear applications. For molten salt cooled reactors employing fluoride based molten salts, a number of nickel based alloys offer reasonable resistance to fluoride corrosion. Recently, fluoride salt cooled reactors have returned to prominence due to their selection as one of the six generation IV reactor designs under consideration. For this reason, the aims of this work were to assess the corrosion of nickel-based alloys and investigate the combined effects of radiation damage and corrosion.

In this work, the corrosion behavior of a nickel-based alloy (GH 3535, procured from the Shanghai Institute of Applied Physics) in LiF-NaF-KF molten salt was explored. The interaction of radiation damage and corrosion was also assessed by damaging the alloy surface using helium ions with energies up to 30keV at an ion fluence of 1017ions/cm2. Accelerated corrosion experiments were conducted at 750°C for times of 10, 100, and 200h with samples characterised using optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and positron annihilation lifetime spectroscopy.

Intergranular attack was the main mode of corrosion observed for samples exposed only to molten salt. However, for helium ion damaged samples, corrosion resulted in a combination of intergranular and intragranular attack. From TEM, the size of the corrosion layer was found to be more than 30 fold larger for the helium ion damage/corroded sample compared with the corroded sample. The mechanistic effects of He ion irradiation on the corrosion of Ni alloys was also investigated. In addition, preferential salt attack towards subsurface damage (an artefact of polishing) was observed showing the influence of surface preparation on corrosion.

Figure 1 - Corroded GH3535 (a) optical, (b) SEM, and (c) TEM