Temperature and orientation dependence of the mechanical properties of Al_0.3CoCrFeNi high-entropy alloy single crystals hardened by non-coherent -phase particles

Ageing of the Al_0.3CoCrFeNi 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, with an average size of length l = = 250-350 nm and width d = 30-45 nm and interparticle distance L = 500-750 nm. It was 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 relative to the quenched single crystals. The deformation of - and [001]-oriented single crystals in the temperature range of 77-973 K is governed by slip and τ _cr are independent of the crystal orientation. It was shown that the strain hardening coefficient Θ = d σ/ d ε and the plasticity ε_pl during tensile strain in - and [001]-oriented single crystals, on the contrary, depend on the crystal orientation. The maximum value of Θ = d σ/ d ε = 3400 MPa and the minimum ε_pl = 8% are observed in oriented single crystals at 77 K. Twinning in -oriented single crystals with the β-phase particles was not detected at tension before failure at 77 and 296 K.

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