About this Abstract |
| Meeting |
2021 TMS Annual Meeting & Exhibition
|
| Symposium
|
Phase Transformations and Microstructural Evolution
|
| Presentation Title |
Super-critical Elasticity: A Challenge to Martensitic Transformation Theory |
| Author(s) |
Haiyang Chen, Yan-Dong Wang, Yang Ren |
| On-Site Speaker (Planned) |
Yang Ren |
| Abstract Scope |
We recently discovered that the first-order stress-induced martensitic transformation (SIMT) of shape-memory-alloys can be completely suppressed by bringing the transformation to a supercritical region [Chen et al., Nature Materials, (2020). https://doi.org/10.1038/s41563-020-0645-4]. In this talk, we will show a supercritical elasticity (SCE) in NiCoFeGa single crystals, which exhibit a large elasticity up to 15.2% strain, with non-hysteretic mechanical responses, a small temperature dependence and high-energy-storage capability and cyclic stability over a wide temperature and composition range. In-situ synchrotron X-ray diffraction shows that the SCE is correlated with a stress-induced continuous variation of lattice parameter accompanied by structural fluctuation. Neutron diffraction and electron microscopy observations reveal an unprecedented microstructure consisting of atomic-level entanglement of ordered and disordered crystal structures, which can be manipulated to tune the SCE. We propose to describe this phenomenon by a modified Landau-theory-based model and show that the SCE is a manifestation of a double-well elastic energy landscape. |
| Proceedings Inclusion? |
Planned: |