Slip and twinning in the [[bar.1]49]-oriented single crystals of a high-entropy alloy

Using [[bar.1]49] - oriented single crystals of an FCC [Fe.sub.20][Ni.sub.20][Mn.sub.20][Cr.sub.20][Co.sub.20] (at.%) high-entropy alloy subjected to tensile deformation, the temperature dependence of critical resolved shear stresses [[tau].sub.cr](T) and the deformation mechanism of slip and twinning are investigated in the early stages of deformation at [epsilon] [less than or equal to] 5% within the temperature interval T = 77-573 K. It is shown that [[tau].sub.cr] increases with decreasing the testing temperature and the [[tau].sub.cr](T) temperature dependence is controlled by the slip of perfect dislocations a/2 . The early deformation stages [epsilon] [less than or equal to] 5% are associated with the development of planar slip by pileups of perfect dislocations a/2 , stacking faults and mechanical twins, which is observed in the temperature interval from 77 to 423 K. A comparison of the temperature dependence Tcr(T) and the development of mechanical twinning is performed between the [[bar.1]49]--oriented single crystals of the [Fe.sub.20][Ni.sub.20][Mn.sub.20][Cr.sub.20][Co.sub.20] high-entropy alloy, the single crystals of the austenitic stainless steel, Fe - 18% Cr - 12% Ni - 2Mo (wt.%) without nitrogen atoms (Steel 316) andHadfieldsteel, Fe - 13% Mn - (1-1.3)% C (wt.%). Keywords: single crystals of a FeNiMnCrCo high-entropy alloy, plastic deformation, slip, twinning, dislocations.