  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.
