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 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 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 τcr by 30–50 MPa in the temperature range of 77–973 K compared to the quenched single crystals. The deformation of [1¯11\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \overline{1}11 $$\end{document}] - and [001]-oriented single crystals in the temperature range of 77–973 K is realized by slip, and τcr are independent of the crystal orientation. It is shown that the strain hardening coefficient Θ = dσ/dε and the plasticity εpl during tensile strain in [1¯11\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \overline{1}11 $$\end{document}]- 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 εpl = 8% are observed in [1¯11\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \overline{1}11 $$\end{document}]-oriented single crystals at 77 K. Twinning in [1¯11\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \overline{1}11 $$\end{document}]- oriented single crystals with the β-phase particles was not detected at tension before failure at 77 and 296 K.