Nano-structuring of a high entropy alloy by severe plastic deformation: Experiments and crystal plasticity simulations

The evolution of microstructure, texture , mechanical properties of an induction melted non-equiatomic Al6Co23.5Fe23.5Mn23.5Ni23.5 (at.%) high entropy alloy subjected to severe plastic deformation was investigated experimentally , by simulations. Analyses using electron backscatter diffraction and transmission Kikuchi diffraction images revealed the evolution of the microstructures. The coarse-grained initial structure was deformed down to an average grain size of 50 nm after a shear strain of 11 by employing the high-pressure compressive shearing process, at room temperature. Transmission electron microscopy analysis showed the presence of nano-twins. The high deformation led to a significant increase in the strength, up to approximate to 1.0 GPa. X-ray diffraction macro-texture analysis revealed a shear texture with the dominance of the B/B {112} (110) -type component whose intensity varied with strain. A two-step Taylor-type polycrystal plasticity simulation approach reproduced the texture by a correlation value of 91%. In the first part of the modeling, grain fragmentation was simulated, while in the second part, grain boundary shearing and deformation twinning were considered together with the operation of {111} (112)-type partial slip. The effect of twinning was also examined in the texture modeling and the simulations estimated that its fraction was less than 2%.

Automated summary

The evolution of microstructure, texture, and mechanical properties of an induction melted non-equiatomic high entropy alloy subjected to severe plastic deformation was investigated. Experimental analyses revealed the deformation of coarse-grained structure into nanocrystalline structure, the presence of nano-twins, and a significant increase in strength. Simulations reproduced the observed texture and estimated the fraction of twinning.