Scientific Highlights2019
HERCULES School 2019 at the Swiss Light Source
In the week of April 1-5 PSI welcomes 20 PhD students and postdocs taking part in the European HERCULES 2019 school on Neutron and Synchrotron Radiation. They will attend lectures and perform two days of practical courses at several beam lines of the Swiss Light Source.
Additive Manufacturing of High Entropy Alloys
Additive manufacturing of high-entropy alloys combines the mechanical properties of this
novel family of alloys with the geometrical freedom and complexity required by modern
designs. An approach to additive manufacturing of high-entropy alloys has been
developed based on 3D extrusion of inks containing a blend of oxide nanopowders (Co3O4 +
Cr2O3 + Fe2O3 + NiO), followed by co-reduction to metals, inter-diffusion and sintering to
near-full density CoCrFeNi in H2. A complex phase evolution path is observed by in-situ X-ray
diffraction in extruded filaments: the oxide phases undergo reduction and the resulting
metals inter-diffuse, ultimately forming the desired fcc-CoCrFeNi alloy (see figure).
Linked to this phase evolution is a complex micro-structural one, from loosely packed oxide
particles to fully-annealed, metallic CoCrFeNi with 99.6 ± 0.1% relative
density. CoCrFeNi micro-lattices are created with strut diameters as low as 100 μm and
excellent mechanical properties at ambient and cryogenic temperatures.
Insights into a well-known disease in ageing populations: Abdominal and popliteal aneurysm
Abdominal aortic aneurysm, an enlargement of the abdominal aorta, may lead to rupture and thus acute health issues and death.
Scanning X-ray imaging enabled new insights in the nano-structure of calcifications associated with abdonimal and popliteal aneurysm and allowed mapping the distribution of nano- and micro-calcifications as well as of collagen, elastin and myofilament as building blocks of connective tissue across samples from human donors.
