Thermally activated deformation of nanocrystalline and coarse grained CoCrFeNiMn high entropy alloy in the temperature range 4.2–350 K

Abstract

Mechanical properties of a nanocrystalline (∼ 60 nm) and a coarse grained (grain sizes ∼ 4 µm) CoCrFeNiMn high entropy alloys were studied in uniaxial compression in the temperature range 4.2–350 K. Temperature dependences of yield strength, flow stress and strain rate sensitivity have been registered and analyzed in the framework of two thermal activation deformation models, that of thermal activation of local barrier overcoming, and that of Peierls valley double kink formation. Microscopic parameters of dislocation interaction with the barriers for thermally activated motion are estimated and low temperature deformation mechanisms are discussed.