The Effect of Aluminium Addition on Solid Solution Strengthening in CoCrFeMnNi High Entropy Alloy: Experiment and Modelling
The effect of aluminium addition to the Cantor alloy in the composition regime of 0.25-5 atomic percent on solid solution strengthening of single phase HEA was investigated using experiments and constitutive modeling. The continuous increase in yield and tensile strength without significant change in ductility is observed for the alloys characterized by almost similar grain sizes (~100 μm) with increasing aluminium content. The constitute modeling of the strengthening has been performed using traditional as well as recently developed models for solid solution strengthening. The constitutive modeling indicated significant contribution of solid solution strengthening due to addition of Al having relatively larger size (̴12%) than the size of elements in the Cantor alloy leading to severe local lattice distortion. The experimental yield strength could be best explained on the basis of large apparent distortion volume of Al atom acting as a stronger barrier to dislocation motion based on the Varvenne model.