Ultrastrong medium-entropy single-phase alloys designed via severe lattice distortion
Seok Su Sohn (Max-Planck-Institut für Eisenforschung)
Alisson Kwiatkowski da Silva (Max-Planck-Institut für Eisenforschung)
Yuji Ikeda (Kyoto University, Max-Planck-Institut für Eisenforschung)
Fritz Körmann (TU Delft - (OLD) MSE-7, Max-Planck-Institut für Eisenforschung)
Wenjun Lu (Max-Planck-Institut für Eisenforschung)
Won Seok Choi (Korea Advanced Institute of Science and Technology)
Baptiste Gault (Max-Planck-Institut für Eisenforschung)
Dirk Ponge (Max-Planck-Institut für Eisenforschung)
Jörg Neugebauer (Max-Planck-Institut für Eisenforschung)
Dierk Raabe (Max-Planck-Institut für Eisenforschung)
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Abstract
Severe lattice distortion is a core effect in the design of multiprincipal element alloys with the aim to enhance yield strength, a key indicator in structural engineering. Yet, the yield strength values of medium- and high-entropy alloys investigated so far do not substantially exceed those of conventional alloys owing to the insufficient utilization of lattice distortion. Here it is shown that a simple VCoNi equiatomic medium-entropy alloy exhibits a near 1 GPa yield strength and good ductility, outperforming conventional solid-solution alloys. It is demonstrated that a wide fluctuation of the atomic bond distances in such alloys, i.e., severe lattice distortion, improves both yield stress and its sensitivity to grain size. In addition, the dislocation-mediated plasticity effectively enhances the strength–ductility relationship by generating nanosized dislocation substructures due to massive pinning. The results demonstrate that severe lattice distortion is a key property for identifying extra-strong materials for structural engineering applications.