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Abstract Nanocrystalline and nanotwinned materials achieve exceptional strengths through small grain sizes. Due to large areas of crystal interfaces, they are highly susceptible to grain growth and creep deformation, even at ambient temperatures. Here, ultrahigh strength nanotwinned copper microstructures have been stabilized against high temperature exposure while largely retaining electrical conductivity. By incorporating less than 1 vol% insoluble tungsten nanoparticles by a novel hybrid deposition method, both the ease of formation and the high temperature stability of nanotwins are dramatically enhanced up to at least 400 °C. By avoiding grain coarsening, improved high temperature creep properties arise as the coherent twin boundaries are poor diffusion paths, while some size‐based nanotwin strengthening is retained. Such microstructures hold promise for more robust microchip interconnects and stronger electric motor components.

Abstract Diffusion is one of the most important phenomena studied in science ranging from physics to biology and, in abstract form, even in social sciences. In the field of materials science, diffusion in crystalline solids is of particular interest as it plays a pivotal role in materials synthesis, processing and applications. While this subject has been studied extensively for a long time there are still some fundamental knowledge gaps to be filled. In particular, atomic scale observations of thermally stimulated volume diffusion and its mechanisms are still lacking. In addition, the mechanisms and kinetics of diffusion along defects such as grain boundaries are not yet fully understood. In this work we show volume diffusion processes of tungsten atoms in a metal matrix on the atomic scale. Using in situ high resolution scanning transmission electron microscopy we are able to follow the random movement of single atoms within a lattice at elevated temperatures. The direct observation allows us to confirm random walk processes, quantify diffusion kinetics and distinctly separate diffusion in the volume from diffusion along defects. This work solidifies and refines our knowledge of the broadly essential mechanism of volume diffusion.

A unique deposition approach combining atomic layer deposition (ALD) and magnetron sputtering was used to fabricate a series of thin film multilayer structures of Al (50 nm) and Al2O3 (ALD, 2.4–9.4 nm) on flexible polymer substrates without breaking vacuum. The multilayers together with 50 nm and 150 nm Al reference films were analyzed by cross-sectional TEM analysis and experimentally strained in biaxial tension to investigate their deformation behavior. Al film stresses and peak widths, measured in situ with Synchrotron X-ray diffraction, are in good agreement with post-mortem surface SEM and through-thickness FIB analysis of the multilayers. It was revealed that brittle cracking of the multilayer can be avoided, and that the lateral and through-thickness crack resistance improve as a function of decreasing oxide layer thickness. An attempt to model the full biaxial yield surface of the multilayers, which remains experimentally challenging, appears to be valid up to 2.4 nm oxide thickness. Model predictions are further compared to compression data, obtained from the unloading segments of the tensile tests. Describing the mechanical behaviour under multiaxial stress conditions is of utmost importance for a diverse understanding of these multilayers across a variety of potential carrier systems and loading cases.