EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Nanoindentation is a commonly accepted technique that measures local mechanical properties. The timescale for a traditional nanoindentation test is on the order of minutes, allowing for spatially varied measurements on a material in the order of 100’s of indents. With the introduction of high throughput (XPM) indentation methods increases, datasets in the tens of thousands and, as recently demonstrated, now up to one million indents map locations can now be gathered as a map looked at both spatially and statistically. These methods include clustering methods to identify similar mechanical properties in different parts of inhomogeneous materials. Nanoindentaion mapping can be taken to the extreme and reach spatial resolution of less than 100nm thereby reaching the resolution of analytical tools that are SEM based. The hardness maps complement maps by EBSD for crystal orientation or WDS for compositional analysis. The effect of alloying elements on the local mechanical properties is probed within the microstructure which is a breakthrough and will allow to gain a deeper understanding of the origin of materials strength and toughness in modern alloys.
The description of a microstructure with a high number of indentation tests will result in an accurate distribution of properties. It can be shown that a sample of 10.000 indentation tests from 1Mio indentation experiments is sufficient to represent the distribution of mechanical properties if machine learning techniques are applied. The accuracy of different clustering methods is tested on a probability distribution function (PDF) that represents a microstructure. By repeated sampling of data from the modeled PDF, it is possible to generate a large sample of simulated data. The data is used to study the robustness of different clustering algorithms.