Strength-ductility balance in an ultrafine-grained non-equiatomic Fe-50 (CoCrMnNi)(50) medium-entropy alloy with a fully recrystallized microstructure

摘要

We explored the phase stability and mechanical properties of an ultrafine-grained non-equiatomic Fe-50(CoCrMnNi)(50) medium-entropy alloy (MEA). The alloy was processed by conventional cold rolling and then annealed at temperatures between 500 degrees C and 800 degrees C. X-ray diffraction revealed that this alloy has a single face-centered cubic structure even below 800 degrees C, where the equiatomic CoCrFeMnNi mostly forms second phases. The kinetics of recrystallization of this alloy demonstrated that a fully recrystallized microstructure with an ultrafine grain size of 0.97 mu m is achieved after annealing at 600 degrees C. Tensile results further revealed that this alloy overcomes the strength-ductility trade-off experienced in nanocrystalline alloys, showing an excellent combination of strength and ductility. The origin of discontinuous yielding behavior in both partially recrystallized and fully recrystallized ultrafine-grained specimens is discussed. (C) 2018 Elsevier B.V. All rights reserved.