High-temperature nanoindentation was used to reveal nano-layer size effects on the hardness of two-dimensional metallic nanocomposites. We report the existence of a critical layer thickness at which strength achieves optimal thermal stability. Transmission electron microscopy and theoretical bicrystal calculations show that this optimum arises due to a transition from thermally activated glide within the layers to dislocation transmission across the layers. We demonstrate experimentally that the atomic-scale properties of the interfaces profoundly affect this critical transition. The strong implications are that interfaces can be tuned to achieve an optimum in high temperature strength in layered nanocomposite structures.
Bibliographical noteFunding Information:
We acknowledge financial support from the European Union through the RADINTERFACES project (Grant No. 263273) and from the Spanish Ministry of Economy and Competitiveness through Grant No. MAT2012-31889 and the use of the microscopy infrastructure available at Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA), University of Zaragoza (Spain). I.J.B., S.J.Z., and N.A.M. gratefully acknowledge support by the Center for Materials at Irradiation and Mechanical Extremes, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award No. 2008LANL1026.
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