Advanced characterization of alloys by using ex-and in-situ high resolution Scanning Transmission Electron Microscopy

Micro- and nano-structure particularities of new materials for specific applications, such as additive manufacturing, are influenced by atomic scale effects. In order to understand and exploit these effects, advanced ex- and in-situ characterization methods are necessary. This paper presents advanced microscopic methods correlated with theoretical calculations that were used to understand the mechanisms of twin formation, spinodal decomposition, pipe diffusion and nucleation in different alloy types. Two- and three-dimensional STEM acquisition of high angular annular dark field images (HAADF) and spectrum image data sets of both dispersive X-ray (EDX) and electron energy loss spectrometry (EELS) are key tools for the localization and identification of the alloying elements with low concentration as well as their influence on stable and metastable phases. [1-6] Information regarding the recrystallization of grains, diffusion of alloying elements and nucleation of new phases at different temperatures was obtained by in-situ high resolution STEM observations. 1. Li JH., Albu M., Hofer F., Schumacher P., Acta Mater. 83 (2015), 187?202. 2. Albu M., et al, Nature Scientific Reports 6 (2016), 31635 3. Gariboldi E., et al, Acta Mater. 125 (2017), 50-57 4. Li JH., et al, Adv. Eng. Mat. 19 (2017), 1600705 5. Haberfelner G., Orthacker A., Albu M., Li JH., Kothleitner G., Nanoscale 6 (2014), 14563-14569 6. Orthacker A, et al, Nature Materials 17 (2018), 1101-1107 7. Part of this research has received funding from the FFG under project no. SP2018-003-006