Dislocation loop coarsening and shape evolution upon annealing neutron-irradiated RAFM steel

Yuan, Q and Chauhan, A and Gaganidze, E and Aktaa, J (2022) Dislocation loop coarsening and shape evolution upon annealing neutron-irradiated RAFM steel. In: Journal of Nuclear Materials, 558 .

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Abstract

Neutron-irradiation induced prismatic dislocation loops contribute to the degradation of materials� mechanical properties. Recent post-irradiation annealing (PIA) investigations on neutron-irradiated reduced-activation ferritic-martensitic (RAFM) steel �EUROFER97� have revealed an almost complete recovery of the mechanical properties. To identify underlying recovery mechanisms, thick-foil annealing experiments on neutron-irradiated EUROFER97 were carried out. It is observed that PIA at 550 °C results in a reduction of initial dislocation loops density with a simultaneous increase in their mean size. This is linked to the dislocation loops shrinkage/annihilation as well as their coarsening/merging phenomena. Moreover, a clear coarsening of the quasi-circular �100� loops into their rectilinear versions and simultaneous shrinkage/annihilation of the ½<111> loops/clusters are observed. The coarsening phenomenon is a non-conservative climb process, which is discussed in terms of the movement of jogs whilst considering the change in the iron's elastic anisotropy with temperature and loops lowest energy directions. Furthermore, the observed interaction of the coarsened �100� loops and thereafter their merging to form large loops of various geometries are presented and discussed. Lastly, a rationalization justifying pronounced microstructural transition from dislocation loops dominated to dislocation tangles dominated microstructure with continued annealing is presented. These thick-foil PIA results complement our previous works and provide complete description of the dislocation loops annealing behaviour in neutron-irradiated EUROFER97. © 2021 Elsevier B.V.

Item Type:	Journal Article
Publication:	Journal of Nuclear Materials
Publisher:	Elsevier B.V.
Additional Information:	The copyright for this article belongs to Elsevier B.V.
Keywords:	Annealing; Coarsening; High resolution transmission electron microscopy; Neutrons; Ostwald ripening; Shrinkage, reductions; Annealing experiments; Dislocation loop; Neutron irradiated; Postirradiation annealing; Prismatic dislocation loop; Recovery mechanisms; Reduced-activation ferritic/martensitic steels; Shape evolution; Thick foils, Neutron irradiation
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	25 Nov 2021 11:32
Last Modified:	25 Nov 2021 11:32
URI:	http://eprints.iisc.ac.in/id/eprint/70477

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