Cyclic superelasticity behavior of Co35Ni35Al28Fe2 single crystals

https://doi.org/10.1016/j.matlet.2025.138728

The effect of cyclic loading/unloading on high-temperature superelasticity and the (B2 + γ/γ’)-microstructure was studied in quenched Co₃₅Ni₃₅Al₂₈Fe₂ single crystals oriented along the [001]_B2-direction. They displayed excellent superelastic response in compression over 100 loading/unloading cycles at 423 K. This superelasticity response is attributed to the high-strength crystallographic [001]_B2 orientation of the B2-matrix and strengthening of the γ-phase due to nanosized γ’-particles. The stress-induced B2-L1₀ martensitic transformation during loading/unloading cycles was accompanied by plastic deformation via twinning of the secondary γ/γ’-phase and dislocation accumulations in B2-matrix around the γ/γ’-phase. This results in a reduction in the critical stress for the martensite formation, stress hysteresis and reversible strain during cycling.