Temperature and Orientation Dependence of the Mechanical Properties of Al0.3CoCrFeNi High-Entropy Alloy Single Crystals Hardened by Non-Coherent beta- Phase Particles

摘要

Aging of the Al0.3CoCrFeNi high-entropy alloy single crystals for 50 h at a temperature of 973 K leads to the precipitation of non-coherent non-equiaxed beta-phase particles with B2-type ordering, average length l =250-350 nm, width d = 30-45 nm, and interparticle distance L = 500-750 nm. It is shown that the interaction of slip dislocations with beta-phase particles is realized by the rounding mechanism. The beta-phase particles increase critical shear stresses tau(cr) by 30-50 MPa in the temperature range of 77-973 K compared to the quenched single crystals. The deformation of [1 over bar 11] - and [001]-oriented single crystals in the temperature range of 77-973 K is realized by slip, and tau(cr) are independent of the crystal orientation. It is shown that the strain hardening coefficient Theta = d sigma/d epsilon and the plasticity epsilon(pl) during tensile strain in [1 over bar 11]- and [001]-oriented single crystals, on the contrary, depend on the crystal orientation. The maximum value of Theta = d sigma/d epsilon = 3400 MPa and the minimum value of epsilon(pl) = 8% are observed in [1 over bar 11]-oriented single crystals at 77 K. Twinning in [1 over bar 11- oriented single crystals with the beta-phase particles was not detected at tension before failure at 77 and 296 K.