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MM: Fachverband Metall- und Materialphysik

MM 16: Microstructure and Phase Transformations III - Precipitaion hardening/ Alloying elements

MM 16.3: Vortrag

Montag, 31. März 2014, 16:15–16:30, IFW B

Phase transformation in Nb-H thin film — •Vladimir Burlaka, Stefan Wagner, and Astrid Pundt — Universität Göttingen, Institut für Materialphysik, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany

Physical properties of nano-sized metal hydrogen systems strongly change with mechanical stress, evolving during hydrogen loading and phase transition. For very thin films stress relaxation processes are expected to be much less efficient compared to thick films. Thus the systems will stay in a high-stress state. This changes the system*s thermodynamics and kinetics [1,2].

In this in-situ STM study we use epitaxial Nb-H thin films of thicknesses with less than 50nm as a model system. By performing constant pressure hydrogen loading sequences on films of different thickness we address differences in hydride precipitation and growth during the phase transformation. To approve and study the role of mechanical stresses conservation, the in-situ STM results are completed by in-situ XRD results providing a macroscopic overview of the sample*s lattice structure during the hydrogen uptake.

Financial support by the DFG via project PU131/12-1 is gratefully acknowledged. Beamtime is kindly provided by the DESY, at PETRA beamline P08.

[1] K. Nörthemann, A. Pundt, Phys. Rev. B, Vol.78, (2008), 014105.

[2] K.Nörthemann K, A. Pundt , Phys. Rev. B 83, (2011), 155420