Superelasticity and Tunable Thermal Expansion across a Wide Temperature Range

• DOI: 10.1016/j.jmst.2016.06.017
• Publication Date: 2016-06-24T19:20:08Z
• Authors: Y.L. Hao; H.L. Wang; T. Li; J.M. Cairney; A.V. Ceguerra; Y.D. Wang; Y. Wang; D. Wang; E.G. Obbard; S.J. Li; R. Yang
• Keywords: Pseudoelasticity; Atmospheric temperature range; Thermal Stability

Materials that undergo a reversible change of crystal structure through martensitic transformation (MT) possess unusual functionalities including shape memory, superelasticity, and low/negative thermal expansion. These properties have many advanced applications, such as actuators, sensors, and energy conversion, but are limited typically in a narrow temperature range of tens of Kelvin. Here we report that, by creating a nano-scale concentration modulation via phase separation, the MT can be rendered continuous by an in-situ elastic confinement mechanism. Through a model titanium alloy, we demonstrate that the elastically confined continuous MT has unprecedented properties, such as superelasticity from below 4.2 K to 500 K, fully tunable and stable thermal expansion, from positive, through zero, to negative, from below 4.2 K to 573 K, and high strength-to-modulus ratio across a wide temperature range. The elastic tuning on the MT, together with a significant extension of the crystal stability limit, provides new opportunities to explore advanced materials.