Refractory High-Entropy Alloys: Design, Fabrication, Characterization, and Nanoparticle Synthesis

High-Entropy Alloys have been a highly researched area of metals ever since their introduction in 2004 by Brian Cantor and Jien-Weh Yeh. In the continued research of High-Entropy Alloys (HEAs), a specific area concerning Refractory High-Entropy Alloys (RHEAs) has emerged for their high-temperature applications. Although RHEAs have maintained high strength and toughness at high temperatures, their low ductility still needs to be addressed. A dataset was created to find correlations between various characteristics of RHEAs and their composition. A set of seven compositions were selected and fabricated. Mechanical tests were run on the seven compositions, and a proposal was written for neutron diffraction tests at Oak Ridge National Lab. In-situ neutron diffraction was performed during mechanical testing on the seven compositions. X-ray diffraction was performed on as-cast samples and post-mortem samples of each composition. The microstructural analysis led to one out of the seven RHEAs being confirmed to contain Transformation Induced Plasticity (TRIP). The six remaining RHEAs were confirmed as a single-phase BCC. Nanoparticles were fabricated from three of the confirmed single-phase compositions and characterized using X-ray diffraction and Scanning Electron Microscope (SEM) Imaging. All three were found to be a single-phase FCC nanoparticle.