In-situ observation of an irradiation creep deformation mechanism in zirconium alloys

We report an original experimental study on a zirconium alloy deformed in situ under ion irradiation and applied stress inside a Transmission Electron Microscope. We observe that dislocations initially pinned on irradiation defects can be unpinned and glide at a lower stress under the effect of the irradiation. It is proposed that unpinning occurs by a local effect of the displacement cascade created by the incoming ion in the vicinity of the pinning point. This novel mechanism of dislocation glide assisted by irradiation is thought to play a crucial role on in reactor irradiation creep of zirconium alloys. (C) 2018 Acta Materialia Inc Published by Elsevier Ltd. All rights reserved.