Comparison of tensile properties between the NiFeCoCr high-entropy alloys

In this study, four NiFeCoCr high-entropy alloys were prepared with different molar ratios. The tensile properties were investigated and discussed. The results showed that adjusting the elemental proportions for solid-solution strengthening is inefficient, because the atomic radius mismatch/misfit volume , Burgers vector magnitude, shear modulus and shear modulus mismatch are quite similar in the different molar ratio alloys. The grain refinement enhances the yield strength effectively, but has limited impact on the strain hardening rate and ductility. The NiFeCo2Cr and NiFe2CoCr alloys exhibit higher ductility than the NiFeCoCr and N2FeCoCr alloys due to the higher strain hardening rate. The higher strain hardening rate of the NiFeCo2Cr and NiFe2CoCr alloys dominantly results from the forest dislocation strengthening promoted by the activated stacking faults with Lomer-Cottrell locks.