Plastic Deformation of Single Crystals of Equiatomic and Non-Equiatomic High- and Medium Entropy Alloys of the Cr-Mn-Fe-Co-Ni and Its Sub-Systems

The plastic deformation behavior of single crystals of the FCC equatomic and non-equiatomic high- and medium-entropy alloys of the Cr-Mn-Fe-Co-Ni and its sub-systems has been investigated in a temperature range of 10-1273 K both in tension and compression. Deformation occurs via slip of the {111}<110> system exclusively in the whole temperature range for all alloys investigated. The CRSS values increase with decreasing temperature, especially below room temperature, so that the concept of ‘stress equivalence’ is obeyed. This is a clear indication that the strength of these alloys should be described by a mechanism based on solid-solution hardening. The CRSS values at 10 K seems to be well scaled by the mean-square atomic displacement from the regular FCC lattice points (calculated based on density-functional theory). Deformation twinning occurs in later stages of deformation at low temperatures below room temperature in many of these alloys. The correlation between twinning stress and the stacking-fault energy will be discussed.