Enhanced diffusion of Cr in 20Cr-25Ni type alloys under proton irradiation at 670 °C

Abstract

Alloy 709 (Fe-20Cr-25Ni-1.5Mo-0.26Nb in weight percentages) and its model alloy (Fe-20Cr-25Ni) were subjected to 2 MeV proton irradiation up to 1.5 displacements per atom at ∼670 °C for 90 h. Significant compositional changes were observed in the irradiated zone of both alloys, which was correlated with the radiation-enhanced diffusion. The radiation-enhanced diffusion coefficient of Cr was experimentally determined by fitting the Cr depletion profiles and theoretically analyzed considering vacancy-assisted lattice diffusion, dislocation pipeline diffusion, etc. The estimation of the radiation-enhanced diffusion in the 20Cr-25Ni type alloy in this study is useful in predicting its performance in radiation damage environment. The methodology of investigating radiation-enhanced diffusion adds to the nuclear-material screening capability of ion-irradiation technologies.