Superelasticity and Shape Memory Effect Under Tension and Compression in the [001]-Oriented Single Crystals of Non-Equiatomic FeNiCoAlTi High-Entropy Alloy

The effect of γ′-phase dispersed particles on the temperature dependence of the stresses of the start of martensitic transformations σcr(T), the shape memory effect, and the superelasticity is investigated depending on aging conditions in the [001]-oriented crystals of the non-equiatomic Fe – 28% Ni – 17% Co – 1.5% Al – 2.5% Ti (at.%) high-entropy alloy under tension/compression. It is shown that σcr(T) during the γ–α′ stressinduced martensitic transformations is independent of the strain method (tension/compression) for small γ′- phase particles with sizes d ≤ 4–6 nm. The value of the reversible strain at tension is 3.5–4.5%, and it is 1.5% at compression. Reasons for strong dependences of the reversible strain and the mechanical hysteresis on the strain method (tension/compression) and particle sizes are discussed.