High-pressure torsion driven mechanical alloying of CoCrFeMnNi high entropy alloy

Fully-dense bulk CoCrFeMnNi high entropy alloy (HEA) has been obtained by high-pressure torsion (HPT) deformation. Elemental, micrometer sized powders were successively mixed in equimolar proportions, consolidated and deformed at 5 GPa using imposed shear strain equivalent up to 100 rotations. Transmission electron microscopy, X-ray diffraction and 3D atom probe tomography were performed to study the microstructure evolution resulting from HPT-induced mechanical alloying. Single-phase, nanocrystalline (grain size of 50 nm) alloy with smaller chromium oxide precipitates (of 7-10 nm) exhibited a hardness of 6700 MPa, which is the highest one reported for as-processed bulk CoCrFeMnNi alloys to our best knowledge. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.