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MM: Fachverband Metall- und Materialphysik
MM 50: Topical Session: Interface-dominated phenomena - Thermodynamics and Microstructure Evolution
MM 50.2: Vortrag
Donnerstag, 19. März 2020, 10:45–11:00, IFW A
Effect of thermally driven phase separation on the (nanoscale) magnetic properties of Fe-Cr — •Vladimir Vojtech1, Robin Schäublin1, Severin Küchler1, Andras Kovacs2, Rafal Dunin-Borkowski2, and Jörg Löffler1 — 1Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Switzerland — 2Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Peter Grünberg Institute, Forschungszentrum Jülich, Germany
Ferritic steel is one of the most promising candidates for deployment as structural material in future fusion reactors. However, the harsh operation conditions, with high temperatures and neutron irradiation, will degrade these materials. In particular, ferritic steel can undergo phase separation leading to Cr-rich α' precipitation, which hardens and embrittles the alloy and may change its magnetic nature. As technological ferritic steels are complex in microstructure and chemistry, studies on fundamental microstructural mechanisms are usually conducted on Fe*Cr model alloys. In this work, we study the thermally driven decomposition in the Fe*Cr system with Cr amounts ranging from 5 to 40 wt.% and annealed for 50 hours to 3 months at 500 °C. Scanning transmission electron microscopy (TEM) with energy-dispersive X-ray spectrometry was used to chemically map the α' phase, while magnetometry, Lorentz TEM and electron holography were deployed to study its impact on the magnetic properties. We will discuss in detail the observed pronounced effect of the decomposition on the magnetic domain size.