Particle Investigation of Mechanically Alloyed Refractory High-Entropy Alloy as Feedstock for Cold Spray Additive Manufacturing

The growing interest in developing component surface protective material technologies capable of withstanding extreme conditions such as high service temperatures led to the exploration of refractory high-entropy alloys (RHEAs). In this research work, MoNbZrTiV and AlNbTaTiV RHEA material combinations were investigated as potential candidates for feedstock materials for cold spray additive manufacturing (CSAM). The two RHEA materials as precursors for developing micron-sized particles were alloyed mechanically through high-energy input following a rigorous material design-of-experiments in account of elemental melting point differences. Detailed particle characterization techniques were employed to gain insights into the RHEA particles’ properties. The particle size distribution was determined, considering its influence on successful particle deposition. Scanning electron micrographs with energy-dispersive spectroscopy analysis showed the manufactured particles' morphological features and chemical homogeneity. The particles’ potential deposition behavior with respect to the substrate’s properties was correlated to the particles’ hardness from nanoindentation. Further, X-ray diffraction results provided insights into the particles’ phase structures which dictated the determined properties. Generally, this study offers a valuable understanding of the properties of mechanically alloyed RHEA particles which can serve as important criteria in producing high-temperature coatings or additively manufactured components in cold spray.