Ultrawide‐Temperature Stable Superelasticity in a Nanoprecipitation‐Strengthened NiTi Strain Glass Alloy

ABSTRACT Superelastic materials exhibiting flag‐shaped hysteresis are valued for their high elasticity and damping capacity, which arise from stress‐induced martensitic transformation and related phase‐transition hysteresis, enabling effective energy absorption and vibration mitigation. However, their widespread use is limited by the narrow operating temperature range and poor functional fatigue. Here, we report an ultrawide temperature range superelasticity spanning from 163 to 373 K, coupled with recoverable strain of 3.5% and exceptionally stable energy dissipation at 183 K. These properties are achieved via a nanoprecipitation‐strengthened two‐step strain glass transition in the Ti 48.3 Ni 51.7 alloy through aging at 573 K for 2 h. In situ transmission electron microscopy shows B2 to R to B19' nanodomains upon cooling, attributed to aging‐induced ultrafine and dispersed Ni 4 Ti 3 nanoprecipitates. These nanoprecipitates not only strengthen the matrix but also stabilize R and B19' nanodomains, enabling stress‐induced reversible phase transformation over a wide temperature range. Phase‐field simulations confirm that precipitation‐induced structural ordering at low temperatures can occur without equilibrium composition in the matrix, maintaining the low transition temperature. This work provides a viable pathway for developing high‐performance superelastic alloys with wide‐temperature and functional fatigue stability, offering significant potential for applications in extreme environments such as aerospace and deep‐sea exploration.