Orientation dependence and asymmetry of the mechanical behavior of (CoCrFeNi)94Ti2Al4 high-entropy alloy single crystals.

The effect of crystal orientation and the deformation method (tension and compression) on the deformation behavior of (CoCrFeNi)₉₄Ti₂Al₄ high-entropy alloy single crystals is studied along two crystallographic orientations ([001] and [111]) at 296 K. It is shown that, at room temperature, the critical resolved shear stresses (τ_cr) are independent of crystal orientation and the deformation method, and the Schmid law is satisfied. The stress-strain response (σ(ε) curves), strain-hardening coefficient (Θ = dσ/dε) and plasticity are found to depend on crystal orientation and the deformation method (tension and compression). The maximum value of Θ is observed in [001]-oriented crystals upon compression during deformation by slip and twinning, and the maximum tensile plasticity in [001]-oriented crystals is due to the development of a planar structure without twinning. In [111]-oriented crystals (under compression from the onset of plastic deformation), instability in the plastic flow is manifested in the appearance of bands of localized deformation, which are absent under tension in crystals of this orientation. [ABSTRACT FROM AUTHOR]