Periodic Reporting for period 2 - NanoHighSpeed (High-speed Deformation and Failure of Materials at the Nanometer Scale)
Reporting period: 2022-05-01 to 2023-10-31
The ERC NanoHighSpeed project will spearhead the development of experimental techniques for investigating the high-speed deformation behavior at the nanoscale. The new development will be based upon nanoindentation testing, a technique that probes the hardness of a sample with a microscopic diamond needle. Nanoindentation testing already grants researchers access to the mechanical properties of a material on a scale of nanometers and micrometers. However, it is currently limited to low loading rates, which are not representative of impacts or collisions. Using innovative hardware and novel experimental methods, the ERC NanoHighSpeed project will turn nanoindentation testing into a powerful tool for high-speed mechanical characterization. This new nanoscale approach will enable us to gain a fundamental understanding of the failure of materials at high strain rates, down to their smallest constituents. This will help develop new materials that can better withstand loads at high deformation speeds. In the long term, safety, environmental and economic benefits will ensue.
In parallel to the hardware developments, we started investigating technologically important materials, such as intermetallic compounds. These materials account for the high temperature strength of the turbine blades used in aircraft engines. The underlying physical mechanism, called “strength anomaly”, has been known since the 1970s. However, it had not yet been experimentally probed whether this positive effect persists under the high-speed deformation conditions of a bird strike, which would be a safety concern. The reason is that intermetallic compounds are tiny components found inside a larger superalloy, which generally cannot be produced in sufficient volume for classical characterization methods. Teaming up with Prof. G.M. Pharr (Texas A&M), we carried out high-speed, high-temperature nanoindentations and reached conclusive evidence ruling out the safety concern.
Furthermore, while developing the high-speed nanoindenter prototype, we uncovered critical limitations of hardware components and correction procedures used in nanoindentation testing. Reporting these shortcomings will avoid misleading data from being published and used in practical applications.