Dresden 2020 – wissenschaftliches Programm

Die DPG-Frühjahrstagung in Dresden musste abgesagt werden! Lesen Sie mehr ...

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MM: Fachverband Metall- und Materialphysik

MM 40: Topical Session: Interface-dominated phenomena - Solutes at Interfaces I

MM 40.1: Topical Talk

Mittwoch, 18. März 2020, 15:45–16:15, IFW A

Using interfaces to move solute atoms and using moved atoms to stop interfaces in steels — •Sybrand van der Zwaag — TU Delft, Delft, the Netherlands

Diffusional phase transformations in steels can involve the partitioning of substitutional alloying elements at the moving austenite-ferrite interface. Under normal isochronal or isothermal annealing conditions the local solute enrichment is spatially coupled to (one side of) the interface at all times. However, in the cyclic partial phase transformation approach, the direction of the moving interface is reverted periodically and the enriched region and the crystallographic interface separate due to a difference in mobility. Hence, reversing the direction of the interface allows for the creation of narrow (nm wide) regions with a higher concentration of substitutional alloying elements within the crystallographically unaffected parent austenitic matrix. Multiple passes towards the enriched rim left behind in the first partial transformation cycle will increase the local enrichment even further. The enriched rim manifests itself as a (chemical) barrier and can block the interface upon final cooling for as much as 150 K. The interface motion and blocking effects are analysed using dilatometry, laser scanning confocal microscopy and Transmission Electron Microscopy.

The chemical boundary engineering (CBE) concept has then been used to create steels in which the sharp boundaries of enriched domains locally halt the advancing martensitic phase fronts, resulting in a nanostructured multiphase steel with exceptional mechanical properties.