Search

For the first time, the shape memory effect (SME) and superelasticity (SE) of [001]-oriented single crystals of a (TiZrHf)50Ni25Co10Cu15 high-entropy alloy (HEA) are studied under compression. SE is observed within a wide temperature range from Ms = 404 K to 530 K. The maximum SE is 4.4%, and the SME is 3%. The (TiZrHf)50Ni25Co10Cu15 HEA single crystals are high-strength materials with the high-temperature SME and SE. [ABSTRACT FROM AUTHOR]

The paper analyzes the mechanical behavior and plastic deformation mechanisms (slip, twinning) in single-crystalline high-entropy fcc alloy (CoCrFeNi)94Ti2Al4 (at %) in relation to the crystal orientation ( , [001]), type of deformation (tension, compression), and heat treatment (quenching, aging at 923 K for 4 h). The analysis shows that after aging at 923 K for 4 h, compared to quenching, the critical shear stress of such crystals increases by 20–30 MPa at 77–973 K due precipitated γ′-phase particles of size 3–5 nm. The onset of their plastic flow, irrespective of the heat treatment, is associated with slip such that their critical shear stress depends neither on the crystal orientation nor on the type of deformation (tension, compression) at 77–973 K. When deformed at 77–973 K after quenching or aging, the and [001] crystals reveal a planar structure with dislocation pileups. In the quenched and aged crystals, twinning occurs after previous tensile slip deformation to 40% at 77 K. The stages of flow curves, the strain hardening coefficient, and the plasticity of the crystals are found to depend on their orientation, test temperature, and heat treatment. The dependences of the strain hardening coefficient of the crystals on their orientation and temperature in tension are discussed. A method is proposed for attaining a high yield strength in single-crystalline high-entropy (CoCrFeNi)94Ti2Al4 under tension at above 296 K. [ABSTRACT FROM AUTHOR]

The temperature interval Δ TSE of superelasticity in [001]-, [ $$ \bar 1 $$23]-, and [ $$ \bar 1 $$24]-oriented Co40Ni21Ga30 (at. %) single crystals strained at compression has been studied. It is established that Δ TSE in the [001]-oriented single crystal amounts to 441 K and the reversible B2-L10 martensite transformations in loaded samples take place at T2 = 698 K. In [ $$ \bar 1 $$23]- and [ $$ \bar 1 $$24]-oriented samples, Δ TSE decreases to 233 K and the superelasticity is observed up to T2 = 523 K. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the dependence of the deforming stresses, shape memory effect, and superelasticity on the orientation of a Co-Ni-Ga single crystal and deformation type. In the study, the structure of Co-Ni-Ga single crystals were investigated upon compression. It reveals that stresses induced by the magnetic field affect the reversible motion of twins in martensite and the reversible change in the crystal sizes.