Development of novel high entropy alloy feedstocks for powder bed fusion using equimolar CoFeNiCuMn composition

Abstract

In this study, six different prediction models were used to generate a script to obtain the High Entropy Alloy (HEA) database from which CoFeNiCuMn was selected. The powder form of the alloy was utilized by high-pressure gas atomization. The samples were characterized by Energy Dispersive Spectroscopy (EDS) for chemical analysis, Electron Back-Scattered Diffraction (EBSD) for grain size determination, X-ray Diffraction (XRD), and Transmission Electron Microscopy (TEM) for phase analysis, and nanoindentation for mechanical properties. Equimolar CoFeNiCuMn samples had single face-centered cubic (FCC) structure, and the +106 μm showed 111 GPa elastic modulus and 2.97 GPa hardness. Also, each sample was evaluated for compatibility with powder bed fusion (PBF) by employing Scanning Electron Microscopy (SEM) for morphology, laser diffraction for particle size distribution, and static and dynamic flow analyses for the flowability examination. Considering all results, it was observed that three tests were sufficient to comparatively assess the novel alloy powders as suitable feedstock for PBF. The −15 µm sample exhibited widespread satellite particles in its morphology, resulting in the lowest apparent density of 4.28 g/cm³ and the highest specific energy of 2.60 mJ/g. In contrast, the other samples, with larger particle sizes, demonstrated discrete powder particles and improved flowability parameters.