Xue, SichuangFan, ZheLawal, Olawale B.Thevamaran, RamathasanLi, QiangLiu, YueYu, K.Y.Wang, JianThomas, Edwin L.Wang, HaiyanZhang, Xinghang2017-12-212017-12-212017Xue, Sichuang, Fan, Zhe, Lawal, Olawale B., et al.. "High-velocity projectile impact induced 9R phase in ultrafine-grained aluminium." <i>Nature Communications,</i> 8, (2017) Springer Nature: https://doi.org/10.1038/s41467-017-01729-4.https://hdl.handle.net/1911/98922Aluminium typically deforms via full dislocations due to its high stacking fault energy. Twinning in aluminium, although difficult, may occur at low temperature and high strain rate. However, the 9R phase rarely occurs in aluminium simply because of its giant stacking fault energy. Here, by using a laser-induced projectile impact testing technique, we discover a deformation-induced 9R phase with tens of nm in width in ultrafine-grained aluminium with an average grain size of 140 nm, as confirmed by extensive post-impact microscopy analyses. The stability of the 9R phase is related to the existence of sessile Frank loops. Molecular dynamics simulations reveal the formation mechanisms of the 9R phase in aluminium. This study sheds lights on a deformation mechanism in metals with high stacking fault energies.engThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.Journal articles41467-017-01729-4https://doi.org/10.1038/s41467-017-01729-4