Ultralarge elastic strain and near-constant stress temperature dependence of Ni–Mn–Ti–Fe–Co eutectic high-entropy alloy

The notable stress hysteresis and strong temperature dependence limit the application of superelastic alloys. In this study, we developed a Ni–Mn–Ti–Fe–Co superelastic high-entropy alloy system with low temperature dependence by integrating high-entropy alloy principles into the Ni–Mn–Ti system through arc-melting technology. By designing a fully eutectic microstructure, the alloy demonstrated stable superelasticity with minimal hysteresis energy dissipation, maintaining a 5% strain across a broad temperature range from 113 to 433 K. Furthermore, it exhibited fully reversible superelasticity of 5% after 12010 cycles at room temperature and demonstrated significant pseudoelasticity of about 8.2% under a high stress of 1600 MPa. Its excellent elasticity, minimal hysteresis energy dissipation, and near-constant stress–temperature dependence over a wide temperature range are attributed to its unique eutectic microstructure and weak first-order phase transformation, making it a promising candidate for applications requiring reliable superelastic performance across diverse temperature environments.