September 2023

Symbolic picture for the article. The link opens the image in a large view.

This month’s image shows the crystal structure of a cobalt-base superalloy at atomic resolution (image width: 12 nm) recorded using scanning transmission electron microscopy. Superalloys of this type are produced to withstand extreme environments with temperatures above 1000 °C. In the image, you can see a change in the atomic ordering: On the bottom left, there is the so-called γ phase which is designed to be a part of the superalloy’s microstructure. Towards the top right, we see another phase, the χ phase, which can form in this alloy after long-term heat treatment and is undesired. By closely looking at the boundary between the two phases, we can learn how one transforms into the other at the atomic level and thereby how to possibly influence the formation of this phase – and ultimately how the properties of the superalloy may be further improved.