INFLUENCE OF COMPOSITION AND MICROSTRUCTURE ON THE FEATURES OF MECHANICAL PROPERTIES OF Co-Cr-Fe-Mn-Ni HIGH ENTROPY ALLOYS

The structure and mechanical properties of high-entropy CoCrFeMnNi (equiatomic) and Co 20 Cr 26 Fe 20 Mn 20 Ni 14 alloys, which differ significantly in the stacking-fault energy, are studied.The structure of the alloys was investigated in three states -as-cast, after homogenizing annealing at T = 1000 °C for 24h and after annealing at T = 850 °C.It was found that in the cast state and after homogenizing annealing at 1000 °C both alloys are single-phase solid solutions with a FCC lattice.Annealing at 850 °C preserves the single-phase state in the equiatomic CoCrFeMnNi alloy, but leads to the appearance of a σ-phase in the Co 20 Cr 26 Fe 20 Mn 20 Ni 14 alloy.The mechanical properties of these alloys were studied in a single-phase state by uniaxial compression tests and hardness measurements.It was discovered, that both alloys in a single-phase state had high plasticity and tendency to force strain hardening.The behavior of hardening coefficients in the area of true strains e = 0.05 -0.17 vary considerably.This may be due to a significant difference in the stacking-fault energy of the investigated alloys.As a result, in Co 20 Cr 26 Fe 20 Mn 20 Ni 14 alloy along with dislocation deformation mechanism there is a high probability of implementation the twinning mechanism.