About this Abstract |
| Meeting |
2026 TMS Annual Meeting & Exhibition
|
| Symposium
|
Thin Films and Coatings: Properties, Processing and Applications
|
| Presentation Title |
D-27: Effect of Seed Layer Lattice Strain Mismatch on Crystallization Temperature of Amorphous NiTi Films |
| Author(s) |
Amirhossein Shafieizad, Jagannathan Rajagopalan |
| On-Site Speaker (Planned) |
Amirhossein Shafieizad |
| Abstract Scope |
NiTi thin films are used as functional materials in MEMS, biomedical devices and robotics due to their shape memory effect (SME). When deposited at room temperature, these films are amorphous and must be crystallized to manifest SME. Metallic seed layers deposited on the surface of NiTi films can substantially reduce the crystallization temperature and limit thermal stresses and nucleation of undesirable precipitates. Here, we systematically examined the effect of lattice strain mismatch between the seed layers and austenite (high temperature NiTi phase) on the crystallization temperature. We varied the strain mismatch by changing the chemical composition of seed layers while keeping their crystal structure (BCC) constant. The experiments show that lower the strain mismatch, greater is the reduction in crystallization temperature, which can exceed 50 K. In addition, by removing the seed layers post-crystallization, we can regain the mechanical and surface properties of pristine NiTi films. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Characterization, Thin Films and Interfaces, Phase Transformations |