LAUSR

High Entropy Alloys (HEAs) such as AlxCrCoFeNiCu, typically consist of five or more alloying constituents in equal or nearly-equal concentrations and are a class of materials with extraordinary mechanical properties [1, 2]. The structural and chemical characterization down to the atomic-scale plays a critical role in understanding the process-structure-property relationships. The presence of many alloying elements with similar atomic number, however, makes the structural characterization a challenge. Here we describe several efforts utilizing advanced scanning transmission electron microscopy (STEM) techniques to quantify the microstructure of AlxCrCoFeNiCu HEAs processed by casting and laser-based rapid solidification methods. Particularly, STEM imaging with high-angle annular dark-field (HAADF) detectors and atomic-scale elemental mapping using energy-dispersive X-ray spectroscopy (EDS) [3] are used to study phase decomposition of the alloys and nanostructured dendrites formed near the phase boundaries.