ERC NanoHighSpeed

The aim of the project is to understand the changes in mechanical properties at high strain rates, considering the influence of the microstructure. In addition to the determination of yield curves and strain rate sensitivity / activation volumes at different strain rates, the project will focus on the mechanical behavior of grain boundaries at high strain rates, whereby mechanisms such as dislocation transmission, shear migration and fracture will be considered. The transition in deformation mechanisms is likely explained by the suppression of thermal activation at high loading rates. The gained knowledge will pave the way for developing new materials that can better withstand loads at high deformation speeds. In the long term, the outcomes of the project will result in safety, environmental and economic benefits.

Due to experimental challenges, it is currently only possible to investigate bulk, homogeneous samples at high loading rates. However small-scale components are also exposed to high loading speeds, such as hard coatings on drilling tooling, or smartphone displays upon impact with the ground to name a few. This highlights the need for developing a new experimental technique.

Nanoindentation testing, which already allows the depth-dependent mechanical characterization at low loading speeds, is an obvious candidate. While the maximum strain rate of conventional nanoindenters is limited both by the electronic components (e.g. low sampling rate) and the dynamics of the device (e.g. low resonant frequency), a nanoindenter prototype based on a system from Alemnis AG is developed in the action with a sampling rate of up to 10⁶ s^-1, which will enable a strain rate of approximately 10⁵ s^-1 .