Fig. 5. Deformation diagram of fcc HEAs.

The critical strain at which the SFs and serrated deformation were activated. In quinary CrMnFeCoNi, the SFs are observed only at a strain value closer to fracture (36.8% in true strain) at 295 K, while at low temperatures, the SFs appear earlier, after ~22.2% at 140 K and ~15.8% at 15 K, respectively. The SFs form more easily in the quaternary CrFeCoNi alloy, where the SFs start at lower deformation strains for all three temperatures. The trend continues for the ternary CrCoNi alloy, where SFs begin to form even at an early stage of deformation at room temperature. The open symbols are the activation strain for serrations at 15 K (the data points are displaced to the left-hand side for clarity), which are substantially higher than the critical strains for SFs.