Producing Refractory High-Entropy Alloys with Cold Spray Additive Manufacturing

Author(s):

Nickolas H. Sotiropoulos, Clara M. Mock, Isaac M. Nault, Heather A. Murdoch, and Jack R. Summers

Abstract:

In this study, 15 different refractory high-entropy alloys were cold sprayed using blended elemental powders and subsequently heat treated. Alloys were analyzed in both the as-sprayed and heat-treated states, evaluating the underlying microstructures resulting from the process. The alloys were categorized as forming single-phase, two-phase, or multiphase structures after heat treatment. Most alloys were found to form uniform porosity throughout the bulk after heat treatment, although some maintained less than 1% porosity, with two alloys forming porosity that followed the interface of the cold spray layers. The goal of this study was to find chemistries that would effectively build up and form a dense single-phase microstructure after heat treatment. Of the 15 alloys evaluated, 3 alloys maintained less than 1% porosity after heat treatment and 5 alloys formed a single-phase microstructure. This study concluded that cold spray additive manufacturing offers a possible transition path to large-scale, high-entropy alloy production for certain alloy chemistries.