A superelastic titanium alloy showing nearly temperature-independent high strength and elastic modulus

Abstract

Lightweight superelastic alloys with temperature-insensitive properties are critical for deep-space exploration devices, yet their development is hindered by the challenge of simultaneously balancing strength, recoverable strain, and temperature sensitivity. Here, we overcome these limitations in a Ti50.5Zr40Nb6Sn2O1.5 alloy through Zr/O co-doping to induce local chemical orders (LCOs). This strategy yields an unprecedented combination of large recovery strain (εr > 4.5%), high superelastic stress (σc > 700 MPa), nearly temperature-independent strength (dσc/dT ≈ 0.59 MPa·K⁻¹), and stable elastic modulus over a wide temperature range from 123 K to 298 K. These properties arise from the elastic confinement imposed on the transformable matrix induced by the LCOs, which enhances resistance to dislocation slip and suppresses martensitic transformation, while the modulus hardening caused by LCOs due to anharmonic atomic vibrations compensates for matrix softening. This work provides a feasible and effective route for developing high-performance superelastic alloys with wide-temperature stability through LCO engineering. This study shows that Zr–O co-doped Ti-based alloys achieve superior strength, superelasticity and temperature insensitivity via oxygen-rich local chemical orders, offering a feasible approach to design high-performance Ti-based superelastic alloys.