| About this Abstract |
| Meeting |
2021 TMS Annual Meeting & Exhibition
|
| Symposium
|
Phase Transformations and Microstructural Evolution
|
| Presentation Title |
Size Effects and Microstructural Evolution of Shape Memory Ceramics during Cyclic Phase Transformations |
| Author(s) |
Isabel R. Crystal, Christopher A. Schuh |
| On-Site Speaker (Planned) |
Isabel R. Crystal |
| Abstract Scope |
Bulk shape memory ceramics (SMCs) exhibit transformation-induced cracking due to mismatch stresses arising at the grain boundaries. Current strategies for mitigating cracking in SMCs involve moving towards smaller volume structures, which feature high surface area for stress relaxation and fewer grain boundaries to minimize transformation stresses. While this approach has proven successful, it typically limits SMCs to sample sizes at the micrometer-scale. Here we explore size effects in cyclic martensitic transformations in millimeter-scale polycrystalline structures to study cracking-induced disaggregation as a function of grain size from ~0.6 to 7.9 microns, and we compare these results to that of a large single crystal. The number of thermal cycles until the polycrystal fully disaggregates is inversely related to grain size while the single crystal sustains no macroscopic damage after >100 cycles. Quantitative calorimetry analysis captures the evolution in heat lost to cracking as the polycrystals gradually disaggregate into loose grains with cycling. |
| Proceedings Inclusion? |
Planned: |