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MM: Fachverband Metall- und Materialphysik

MM 6: Topical session (Symposium MM): Correlative and in-situ Microscopy in Materials Research

MM 6.3: Vortrag

Montag, 1. April 2019, 12:30–12:45, H44

Cryo-atom probe tomography for in-situ diffusion measurement of H at crystal defects — •Peter Felfer — Institute for General Materials Properties, Department of Materials Science, Friedrich-Alexander Universität Erlangen-Nürnberg

The diffusion of H in metallic materials is a highly important phenomenon in for both hydrogen energy conversion and structural integrity of materials. Historically, diffusion experiments at the crystal defect scale have not been possible due to measurement instrumentation limitations. As a result, the theoretical description of the phenomenon lacks experimental data to be compared to on individual defects. In recent years atom probe tomography has shown to be capable of delivering such data. About a decade ago atom probe has first been used to locate H, more specifically D in metals. Initially, deuteration through gas charging was used to create D dissolution in thermodynamic equilibrium, which was then supplemented by electrochemical charging, which can be used to create supersaturated states. Since for Fe, the most common base metal in engineering in the form of steel, has very low residual solubility for H even at room temperature, but still a high diffusion coefficient, cryo-cooling can be used to *freeze* D in the material and trigger diffusion only at controlled time intervals. In this talk, I will present first results of such a diffusion experiment. I will also present the design and first results of direct H (no D) measurements in metallic materials using a new atom probe with very low H background.