Dresden 2026 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 30: Interface Controlled Properties, Nanomaterials, and Microstructure Design II
MM 30.3: Talk
Thursday, March 12, 2026, 10:45–11:00, SCH/A215
Vacancy-mediated extreme abnormal grain growth in inert gas-condensed nanocrystalline Pd–Au: when what’s missing runs the show! — Fabian Andorfer1, Johannes Wild2, Jürgen Markmann3,4, Markus Ziehmer1, Jules M. Dake1, Torben Boll2, Dorothée Vinga Szabó2,5,6, Stefan Wagner2, Astrid Pundt2,5, and •Carl E. Krill III1 — 1Inst. of Functional Nanosystems, Ulm University — 2Inst. for Applied Materials, KIT — 3Inst. of Hydrogen Technology, Helmholtz-Zentrum Hereon — 4Inst. of Materials Physics and Technology, TUHH — 5Inst. of Nanotechnology, KIT — 6Karlsruhe Nano Micro Facility (KNMFi), KIT.
Inert gas-condensed Pd–Au exhibits extreme abnormal grain growth (AGG), marked by a small number of grains growing dendritically through a matrix of nanocrystallites, eventually reaching sizes of 100 µm or more. The triggers for rapid growth of abnormal grains (emergence) and for maintaining this growth advantage (persistence) remain unclear. Annealing under hydrogen accelerates emergence without altering grain morphology, suggesting that the ∼ 5 vol% porosity inherent to inert gas condensation not only pins matrix/matrix grain boundaries (GBs) but also governs where and when abnormal grains emerge. In nano-Pd–Au, pores can coarsen by vacancy diffusion along GBs, with larger pores growing at the expense of smaller ones. Small-angle x-ray scattering measurements support such an evolution in pore-size distribution. Vacancy transport, rather than variations in boundary mobility, appears to establish the spatiotemporal conditions for AGG in this system.
Keywords: abnormal grain growth; small-angle x-ray scattering; vacancy diffusion; palladium; gold