About this Abstract |
| Meeting |
MS&T25: Materials Science & Technology
|
| Symposium
|
Microstructural Control in Materials Processing: Role of Phase Transformation Pathways
|
| Presentation Title |
On the balance between strengthening effect and shape memory properties in NiTiHf-based alloys with different Al additions and complex precipitation structure |
| Author(s) |
Flavia Gallo, Eitan Hershkovitz, Soumya Bandyopadhyay, Michael Tonks, Honggyu Kim, Michele Manuel |
| On-Site Speaker (Planned) |
Flavia Gallo |
| Abstract Scope |
Achieving balance between high strength and shape memory behavior in NiTi-based high-temperature shape memory alloys remains a key challenge, as strengthening mechanisms can suppress martensitic transformation. This study investigates the effect of aluminum additions on the transformation behavior and microstructure of NiTiHfAl alloys. A 2% Al addition slightly lowers the martensitic transformation temperature, while 4% fully suppresses it, despite increasing ultimate compressive strength to 2.2 GPa. Aging the 4% Al alloy leads to the formation of two distinct nanoscale precipitates. These contribute to strengthening but introduce elastic strain and alter matrix chemistry, collectively hindering transformation. The study focuses on how phase transformation pathways, driven by compositional tuning, influence precipitation behavior and mechanical and thermal performance. Advanced electron microscopy and phase-field modeling quantified lattice misfit and interfacial strain energies, revealing the thermodynamic origin for the complete suppression of martensitic transformation at higher Al contents, offering valuable insight for future HTSMA design. |