In situ microscopy of nano-sized materials: challenges and opportunities
Jeff Th. M. De Hosson
Department of Applied Physics
University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands
e-mail:j.t.m.de.hosson@rug.nl
In the field of microscopy fundamental and practical reasons still remain that hamper a straightforward correlation between microscopic structural information and physical properties in nano-sized materials. We argue that one should focus in particular on in-situ rather than on postmortem observations of the microstructure.
In this presentation several examples will be presented to exemplify this viewpoint. First, we will show the excitements of the nanocluster deposition by starting with the basic building block of Fe, Nb, Mo and Co, i.e. the structure and properties of a single cluster studied with high-resolution transmission electron microscopy, followed by an in-situ TEM study of the coalescence and diffusion of clusters (sizes ranging between 3 nm and 10 nm) leading to the growth of nano-structured metal films. Next, in situ TEM nanoindentation and in-situ straining studies are discussed on crystalline and non-crystalline metallic materials. In-situ TEM displacement-controlled indentations in crystalline alloys show that many dislocations are nucleated prior to the initial macroscopic yield point and that the macroscopic yield event is associated with the rearrangements of the dislocations. In situ TEM straining and compression of amorphous metals permit an evaluation of the thickness of the liquid-like layer formed due to heat evolution after shear band development. An intriguing question is why and how nucleation and propagation of these shear bands are affected by the size of the system, and would it be possible to suppress brittleness and enhance ductility just by changing the size of the samples?
It is concluded that recent advances in in-situ microscopy can provide new insights about the nucleation and propagation of shear bends, dislocations and cracks in nano-sized metallic systems.
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