Samaee Vahid, Gatti Riccardo, Devincre Benoit, Pardoen Thomas, Schryvers Dominique, Idrissi Hosni
Electron Microscop for Materials Science (EMAT), Department of Physics, University of Antwerp, Antwerp, Belgium.
Laboratoire d'Etude des Microstructures, UMR104 CNRS-ONERA, 29 av. de la division Leclerc, Chatillon, France.
Sci Rep. 2018 Aug 13;8(1):12012. doi: 10.1038/s41598-018-30639-8.
Intrinsic dislocation mechanisms in the vicinity of free surfaces of an almost FIB damage-free single crystal Ni sample have been quantitatively investigated owing to a novel sample preparation method combining twin-jet electro-polishing, in-situ TEM heating and FIB. The results reveal that the small-scale plasticity is mainly controlled by the conversion of few tangled dislocations, still present after heating, into stable single arm sources (SASs) as well as by the successive operation of these sources. Strain hardening resulting from the operation of an individual SAS is reported and attributed to the decrease of the length of the source. Moreover, the impact of the shortening of the dislocation source on the intermittent plastic flow, characteristic of SASs, is discussed. These findings provide essential information for the understanding of the regime of 'dislocation source' controlled plasticity and the related mechanical size effect.
由于采用了一种将双喷电解抛光、原位透射电镜加热和聚焦离子束相结合的新型样品制备方法，对几乎无聚焦离子束损伤的单晶镍样品自由表面附近的本征位错机制进行了定量研究。结果表明，小尺度塑性主要由加热后仍存在的少量缠结位错转变为稳定的单臂源（SASs）以及这些源的连续运作所控制。报道了单个SAS运作导致的应变硬化，并将其归因于源长度的减小。此外，还讨论了位错源缩短对SASs特有的间歇性塑性流动的影响。这些发现为理解“位错源”控制的塑性机制及相关力学尺寸效应提供了重要信息。
