The equiatomic face-centered cubic high-entropy alloy CrMnFeCoNi was severely deformed at room and liquid nitrogen temperature by high-pressure torsion up to shear strains of about 170. Its microstructure was analyzed by X-ray line profile analysis and transmission electron microscopy and its texture by X-ray microdiffraction. Microhardness measurements, after severe plastic deformation, were done at room temperature. It is shown that at a shear strain of about 20, a steady state grain size of 24 nm, and a dislocation density of the order of 10¹⁶ m⁻² is reached. The dislocations are mainly screw-type with low dipole character. Mechanical twinning at room temperature is replaced by a martensitic phase transformation at 77 K. The texture developed at room temperature is typical for sheared face-centered cubic nanocrystalline metals, but it is extremely weak and becomes almost random after high-pressure torsion at 77 K. The strength of the nanocrystalline material produced by high-pressure torsion at 77 K is lower than that produced at room temperature. The results are discussed in terms of different mechanisms of deformation, including dislocation generation and propagation, twinning, grain boundary sliding, and phase transformation.

Equal channel angular pressing (ECAP) is a severe plastic deformation (SPD) technique leading to refinement of the grain size of materials to submicron or even nano-size length scales. As a result SPD processed materials simultaneously possess high strength and moderate ductility and therefore have a high potential for technical applications. Because of this, much work has been devoted to the evolution of microstructure and texture and their relation to the mechanical properties. However, pressing materials through an angled channel is a complicated deformation process leading to deformation heterogeneities across the billet cross section manifested in gradients of microstructure and texture. Therefore, it is the aim of the present paper to give an overview focusing on the ECAP specific deformation heterogeneities and their related strength gradient in the billets produced. Based on the results reported, which are gained from experiment and simulation, some general conclusions on minimizing the deformation heterogeneities in ECAP are drawn.

An equiatomic high-entropy alloy CrMnFeCoNi was severely deformed at room temperature by high pressure torsion up to shear strains of about 170. Its microstructure and texture were analyzed by X-ray diffraction (X-ray line profile analysis and X-ray microdiffraction, respectively). It is shown that at a shear strain of about 20 a steady state domain/grain size of 24 nm and a dislocation density of 3 × 10 16 m-2 is reached, while the twin density goes over a maximum of 2% at this strain. The texture developed is typical for sheared face-centred cubic metals, but it is extremely weak. The results are discussed in terms of the mechanisms of deformation, including dislocation slip, twinning and grain boundary sliding.