High-throughput solid solution strengthening characterization in high entropy alloys

While some high entropy alloys (HEAs) have been shown to display remarkable combinations of properties, exploration of the extensive multicomponent space by conventional methods is experimentally intractable. Thus, identifying and developing high-throughput screening methods is paramount to alloy design. Here, an experimental methodology is developed for rapid yield strength estimations of single-phase HEAs, which involves the production and testing of a compositionally-graded sample made by a diffusion-multiple approach. The sample is analyzed by a combination of nanoindentation and microstructural characterization, where the nanohardness results are analyzed by different conversion equations to determine yield strength. The values estimated by nanohardness agree with bulk tensile properties for a total of 8 compositions. Both are compared to a solid solution strengthening model, again yielding a good correlation. The experimental and simulation results indicate that, in this system, the strength is maximized when the atomic size mismatch is maximized. Furthermore, it is necessary to consider the strain hardening of these alloys to accurately estimate their strength by nanoindentation. A pathway is presented here. This work shows that high-throughput methodologies for predicting and measuring properties are promising for designing new HEAs with desirable combinations of properties.