CD Laboratory for nanoscale phase transformations

Changes on the nanoscale under stresses such as pressure and temperature determine the properties of modern materials during their use. This CD Laboratory investigates these physico-chemical changes in semiconductor and steel systems.

Highly stressed steel components, safety-relevant for vehicle bodies or exposed to the extreme conditions in the engine injection system, are coated with various material systems to protect them from corrosion or wear. The coatings and the base material are perfectly matched to the necessary requirements thanks to their alloy composition and structure.

However, new phases can form at the joint areas, the interfaces and grain boundaries of the systems, causing unwanted effects. In the case of ultra-high-strength steels and Zn coatings, for example, this can be liquid metal embrittlement during welding or forming. Another problem occurs, for example, in the semiconductor germanium-tin, a promising material for optical applications and compatible with silicon technology. This alloy is not particularly temperature-stable and segregates at relatively low temperatures.

This CD Laboratory investigates these and related processes in order to find ways of influencing them and, ideally, preventing them altogether. Segregation, diffusion and formation processes are analysed under controlled thermal conditions live (in-situ) and as snapshots (ex-situ) using various methods such as electron diffraction, electron microscopy and spectroscopy, resolved down to the atomic level and described in detail.

In this way, the CD Laboratory aims to better understand the physico-chemical processes at semiconductor layers and phase boundaries in various coating-steel systems. The systematic approach will lead to significant contributions in the fields of electron microscopy, semiconductor and metal physics and help industrial partners to further optimise their products.