Proton Irradiation-Decelerated Intergranular Corrosion of Ni-Cr Alloys in Molten Salt

TL;DR

Proton irradiation can slow down intergranular corrosion in Ni-Cr alloys within molten salt at high temperatures by enhancing diffusion and reducing void formation, challenging the usual perception of radiation damage as solely detrimental.

Contribution

This study reveals that proton irradiation can decelerate corrosion in Ni-Cr alloys in molten salt, demonstrating a positive effect of radiation on material corrosion behavior.

Findings

Proton irradiation reduces intergranular void depth caused by corrosion.

Radiation-enhanced diffusion replenishes alloy vacancies more rapidly.

Irradiation can have beneficial effects on corrosion in high-temperature molten salt environments.

Abstract

The effects of ionizing radiation on materials often reduce to "bad news." Radiation damage usually leads to detrimental effects such as embrittlement, accelerated creep, phase instability, and radiation-altered corrosion. This last point merits special attention. Elucidating synergies between radiation and corrosion has been one of the most challenging tasks impeding the deployment of advanced reactors, stemming from the combined effects of high temperature, corrosive coolants, and intense particle fluxes. Here we report that proton irradiation significantly and repeatably decelerates intergranular corrosion of Ni-Cr alloys in molten fluoride salt at 650C. We demonstrate this effect by showing that the depth of intergranular voids resulting from Cr leaching into the salt is reduced by the proton irradiation alone. Interstitial defects generated from proton irradiation result in radiation-enhanced diffusion, more rapidly replenishing corrosion-injected vacancies with alloy constituents, thus playing the crucial role in decelerating corrosion. Our results show that in industrially-relevant scenarios irradiation can have a positive impact, challenging our view that radiation damage always results in negative effects.