The effect of alloying on the mechanical properties of single crystals of high-entropy alloys

The mechanical properties of the (CoCrFeNi)(93)Al-7 and (CoCrFeNi)(94)Al4Ti2 (at %) high-entropy alloys were studied in the single-phase state along [001]- and [(1) over bar 11] -orientation under tensile strain. It was established that initial yield behavior along these orientations is governed by a dislocation slip mechanism and the critical resolved shear stresses for slip are independent of crystal orientation within a wide temperature range of 77-973 K. The strain hardening coefficient Theta = d sigma/d epsilon and plasticity depend on the crystal orientation. It has been found that in the (CoCrFeNi)(94)Al4Ti2 high-entropy alloy single crystals, the dependence of Theta = d sigma/d epsilon and plasticity on the crystal orientation are due to the influence of alloying with Ti atoms on the strain localization and the value of the stacking fault energy. The maximum Theta = d sigma/d epsilon of 1730-2320 MPa and the maximum plasticity of 40-48% were found in [(1) over bar 11] - and [001]-oriented crystals of the (CoCrFeNi)(94)Al4Ti2 high-entropy alloy, respectively, within the temperature range of 77-296 K.