Structure and properties of equiatomic CoCrFeNiMn alloy fabricated by high-energy ball milling and spark plasma sintering

High-entropy alloy CoCrFeNiMn was produced by short high energy ball milling (90 min) and spark plasma sintering (10 min at 1073 K). Co-existence of two fcc-phases with lattice parameters 0.360 nm and 0.356 nm was demonstrated via HRTEM, XRD and other methods. The matrix fcc-phase with larger parameter transforms into the more compact phase during annealing up to 1273 K. Similar transformation partially occurs after SPS. Some elements, mostly Cr and Mn, released from the matrix phase and formed precipitates. Up to three types of precipitates, with characteristic size from 10-30 nm to 200-300 nm, have been detected and studied. Electric and thermal properties of the material, measured at room and elevated temperature, shown that lattice thermal conductivity plays an important role, along with free electron thermal conductivity. (C) 2019 Elsevier B.V. All rights reserved.