High-speed Deformation and Failure of Materials at the Nanometer Scale

For a sustainable economy, it is paramount to create robust, durable products.

In the case of mobile phone displays, cutting tools and other products subjected to impact loading, this means finding ways to avoid brittle failure at high stain rates.

This is currently difficult, since little to no fundamental understanding of the deformation mechanisms at high strain rates exists. This is largely owing to the fact that no methods are available for nanoscale investigations.

By developing nanoindentation into a new tool for high strain rate testing, we will achieve a groundbreaking improvement of the spatial resolution of high strain rate mechanical testing by 10^6.

This extraordinary improvement will be possible through simultaneous advances in hardware and experimental methods.This new nanoscale approach will enable a breakthrough in the fundamental understanding of the mechanical behavior of materials at high strain rates down to their constituent microstructural elements.

We will isolate single grain boundaries and measure their individual contribution to strength and embrittlement as a function of strain rate, crystal structure and grain boundary energy.

The local resistance to dislocation transmission, migration and fracture will be correlated to the overall Hall-Petch strengthening behavior of the polycrystal.

The payoff will be a better understanding and predictability of embrittlement events at high strain rates.A second breakthrough will be made possible in understanding the interplay between plasticity and brittle fracture at high strain rates in some of the technologically most important hard coatings, including toughened glass used in mobile phone screens and TiAlN based coatings, commonly used in tooling.

We will examine the recent hypothesis of a possible regain in ductility and systematically investigate the influence of the microstructure and residual stress. This will open up new paths for optimizing the durability of future coating systems.