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

Aging of the Al 0.3 CoCrFeNi high-entropy alloy single crystals for 50 h at a temperature of 973 K leads to the precipitation of non-coherent non-equiaxed β-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 β-phase particles is realized by the rounding mechanism. The β-phase particles increase critical shear stresses τ cr by 30–50 MPa in the temperature range of 77–973 K compared to the quenched single crystals. The deformation of [ 1 ¯ 11 ] - and [001]-oriented single crystals in the temperature range of 77–973 K is realized by slip, and τ cr are independent of the crystal orientation. It is shown that the strain hardening coefficient Θ = dσ/dε and the plasticity ε pl during tensile strain in [ 1 ¯ 11 ]- and [001]-oriented single crystals, on the contrary, depend on the crystal orientation. The maximum value of Θ = dσ/dε = 3400 MPa and the minimum value of ε pl = 8% are observed in [ 1 ¯ 11 ]-oriented single crystals at 77 K. Twinning in [ 1 ¯ 11 ]- oriented single crystals with the β-phase particles was not detected at tension before failure at 77 and 296 K.