Early stages of irradiation induced dislocations in urania

The early stages ofnucleation and growth ofdislocations byirradiation in urania is clarified based on the combination of experiments and atomistic calculations. It is established thatirradiation induceddislocations follow a five stage process: (i) point defects are first created byirradiation, (ii) they aggregate into clusters, (iii) from which nucleate Frank loops, (iv) which transform into unfaulted loops via Shockley that in turn grow, and (v) finally reorganize into forestdislocations. Stages (i) –(iii) participate in the lattice expansion while the onset of lattice contraction starts with stage (iv), i.e., when unfaulted loops nucleate.Irradiation induceddislocations operate in the spontaneous recombination regime, to be opposed to thethermal diffusion regime. Body of arguments collaborates to this statement, the main one is the comparison between characteristic distances estimated from the dose rate(Vat/(K0×τ))13 and from thediffusion coefficient (D×τ)12. Such a comparison identifies materials underirradiation as belonging either into the recombination regime or not.

Source: Applied Physics Letters - November 4, 2016 Category: Physics Authors: A. Chartier, C. Onofri, L. Van Brutzel, C. Sabathier, O. Dorosh and J. Jagielski Source Type: research