Ex- and in-situ high-resolution microstructure investigations of powders and additive manufactured parts

In recent years, there has been increased interest in material characterization at very high resolution. Whether aged, old, in use or newly developed materials, the micro- and nanostructure morphology, chemical composition and functionality are crucial for the fundamental understanding and therefore for field-specific developments.

Within this paper, a couple of scanning and transmission electron microscopy (SEM and S/TEM) characterization methods were used for advanced microstructural analysis of the powders as well as of the as-built and heat treated additive manufactured parts of Al-alloys and N700 steel.

Evolution of the microstructure during the heat-treatment was studied in detail in order to better understand the mechanical properties of the printed parts.

Scanning TEM acquisition of high angular annular dark field images (HAADF), as well as both X-ray (EDX) and electron energy loss spectrometry (EELS) spectrum images, were used to localize and identify the elements and their stable and metastable phases.

Ex- and in-situ measurements were performed in order to provide information regarding the crystallization of amorphous phases and coarsening/shrinking of grains, diffusion of alloying elements and nucleation of secondary phases at different temperatures.