Effect of Electron Beam Treatment on the Structure, Properties and Fracture Behavior of High-Entropy Co - Cr - Fe - Mn - Ni Alloy

A high-entropy Co - Cr - Fe - Mn - Ni alloy with a non-equiatomic composition obtained by the method of wire arc additive manufacturing (WAAM) is studied. The stress-strain curves due to tension of the alloy are analyzed in the initial condition and after electron beam treatment. The strength and ductility parameters, the nano- and microhardness, and the tribological properties are determined as a function of the energy density of the electron beam. Analysis of the fracture surface after the electron beam treatment and of the regions of ductile fracture shows the presence of a region with a banded (lamellar) structure. The scalar dislocation density is shown to vary nonmonotonically and to attain a maximum value of about 5.5 x 10(10) cm (- 2) at a distance of 25 mu m from the irradiated surface. The electron beam treatment lowers the strength and ductility properties of the high-entropy alloy. It is assumed that the defects produced in the surface layer under such a treatment may be responsible for lowering of the strength and ductility of the alloy.