Novel technologies for, e.g., energy production, transportation, and construction demand novel materials that tolerate extremes in temperature, stress, strain rate to an extent that sometimes far exceed the limits of most advanced materials to date. Nanolaminate (NL) structures involving a high density of structural interfaces have been demonstrated as promising to meet these needs due to their unusual mechanical, electrical and magnetic properties, and radiation damage tolerance. However, up to now, only very few NL systems such as Cu/Nb laminates with nanometer-scale layers have been sufficiently studied and optimized to reach unique combinations of outstanding properties including ultra-high strength and plastic deformability, thermal stability, shock resistance, and high resistance to ion-irradiation-induced damage [1-3]. As a matter of fact, and similarly to most nanostructured materials, the ultra-high strength of the NL structures is reached most often at the expense of a poor ductility, with negative impact on the transfer to engineering applications.

In the present work, we use the PI-95 TEM Pico-indenter holder and the Push-to-Pull (PTP) device (Bruker.Inc) to perform quantitative in-situ tensile tests at room temperature on a-Al2O3 and Al/a-Al2O3 NL films inside a transmission electron microscope. The results show that exposure to electron beam under tension leads to a giant ductility (more than 50%) of theses system. Unexpectedly, high plastic flow in the a-Al2O3 layers combined with intense grain boundary sliding at the Al/a-Al2O3 interface is observed. The origin of such behaviour is explained based on large MD simulations. These findings open windows for the improvement of the ductility of hybrid crystal/amorphous NLs.

[1] J.S. Carpenter, S.J. Zheng, R.F. Zhang, S.C. Vogeld , I.J. Beyerleinc, N.A. Maraab, Philos. Mag., 2013, 93, 718.

[2] N.A. Mara, D. Bhattacharyya, R.G. Hoagland, Scripta Mater., 2008, 58, 874.

[3] W.Z. Han, E.K. Cerreta, N.A. Mara, I.J. Beyerlein, J.S. Carpenter, S.J. Zheng, C.P. Trujillo, P.O. Dickerson, A. Misra, Acta Mater., 2014, 63, 150.