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MM: Fachverband Metall- und Materialphysik

MM 35: Topical session (Symposium MM): Correlative and in-situ Microscopy in Materials Research

MM 35.7: Vortrag

Donnerstag, 4. April 2019, 12:45–13:00, H45

In situ TEM observation of phase decomposition in NiAu nanoparticles derived from solid-state dewetting of bilayer metal thin films — •Johanna Schubert¹, Christian Wiktor¹, Simon Kraschewski¹, Patrick Herre², Mingjian Wu¹, Wolfgang Peukert², and Erdmann Spiecker¹ — ¹Institute of Micro-and Nanostructure Research, FAU, Erlangen, Germany — ²Institute for Particle Technology, FAU, Erlangen, Germany

Solid-state dewetting of multilayer metal thin films is a novel method to tailor alloy nanoparticles in composition, size, shape and orientation by varying layer thicknesses and dewetting parameters. Alloy nanoparticles produced in this way are ideal model systems for studying fundamental aspects of phase transformation in confined volumes. By dewetting of Ni-Au bilayers AuxNi1-x alloy nanoparticles with various compositions were produced. Despite a large miscibility gap in the Ni-Au system solid solution particles were obtained by fast quenching. Subsequent annealing at lower temperature allowed us to study the phase decomposition under controlled conditions. Two decomposition pathways were observed resulting in particles with Au-rich phases on the outer facets and particles with lamellar structure of alternating Ni- and Au-rich phases. In situ TEM was applied to gain deeper insight into the role of nanoparticle morphology on the mechanisms and kinetics of phase decomposition. High resolution analysis of particle cross sections revealed closely spaced 1/2[110]-typed edge dislocations at the phase boundaries. The dislocations compensate the large lattice misfit of > 10 % between the Ni- and Au-rich phases.