Roles of vacancy/interstitial diffusion and segregation in the microchemistry at grain boundaries of irradiated Fe–Cr–Ni alloys

Abstract

This work presents a detailed analysis of the diffusion fluxes near and at grain boundaries of irradiated Fe-Cr-Ni alloys, induced by preferential atom-vacancy and atom-interstitial coupling. The diffusion flux equations werebased on the Perks model formulated through the linear theory of the thermodynamics of irreversible processes. The preferential atom-vacancy coupling was described by the mobility model, whereasthe preferential atom-interstitial coupling was described by the interstitial binding model. The composition dependence of the thermodynamic factor was modeled using the CALPHAD approach. The calculated fluxes up to 10dpa suggested the dominant diffusion mechanism for chromium and iron is via vacancy, while that for nickel can swing from the vacancy to the interstitial dominant mechanism. The diffusion flux in the vicinity of a grain boundarywas found to be greatly modified by thesegregation induced by irradiation, leading to the oscillatory behavior of alloy compositions in this region.

Synergies Between ' and Cavity Formation in HT-9 Following High Dose Neutron Irradiation

“…For instance, α' has been shown to precipitate in volume fractions as large as 4% with sub-10 nanometer sizes [2], but little attention has been paid towards the spatial and hence synergistic effects between α' and cavity formation. Internal interfaces within a microstructure have been shown to act as point defect sinks under irradiation [3,4] and hence one would anticipate if precipitation occurs prior to the on-set of steady state swelling that phase instabilities could contribute to the swelling resistance of HT-9.…”

Thermodynamic and kinetic modeling of grain boundary equilibrium segregation of P in α-Fe

“…However, a more rigorous model based on the linear response theory, with a clear correspondence between the D-coefficients and the L-coefficients to describe the effect of interaction and correlation among elements is needed for multicomponent alloys. Progress in this regard has been made recently in the modeling of radiation-induced segregation of Fe-Cr-Ni alloys [18]. The details of modeling radiation induced segregation is beyond the scope of this work.…”

Irradiation stability and induced ferromagnetism in a nanocrystalline CoCrCuFeNi highly-concentrated alloy

“…Within the nuclear materials community, this interpretation of the RIS phenomenon is known as the Inverse Kirkendall Effect (IKE) [62]. IKE has been extensively used over the years to explain RIS within the microchemistry of austenitic stainless steels under irradiation [59,[63][64][65][66][67]. These steels are cast in the ternary system Fe-Cr-Ni which is homologous to the herein studied quinary Co-Cr-Cu-Fe-Ni.…”