Solid Solution Strengthening in High-Entropy Alloys

This book chapter discusses solid solution strengthening (SSS) as one of the main hardening mechanisms in high-entropy alloys (HEAs) that form basis as one of its core effects (lattice distortion). The various techniques used to quantify SSS and the role of different substitutional and interstitial elements/atoms in improving the strength of HEAs are outlined in detail. This review provides a good assessment on ways to enhance the mechanical properties of HEAs to suit the extreme demands of modern engineering applications. Based on theoretical modeling and experimental validation, Al and Nb provide superior substitutional SSS in face-centered cubic and body-centered cubic crystal structures, while carbon has a 50% more effect on improving the mechanical properties of HEAs than in stainless and twinning-induced plasticity steels. Moreover, a detailed description of the application of machine learning in design of HEAs shows that trial and error can eliminated in identifying HEAs with exceptional yield strength. The atomic size difference should be used to evaluate the lattice distortion effect.