|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Phase Transformations and Microstructural Evolution
||F-81: Effect of Composition and Thermal Processing on Transformation Characteristics and Equilibrium Phase Stability in NiTiHf High Temperature Shape Memory Alloys
||Tejas Umale, Bradley Tomes, Ibrahim Karaman, Anjana Talapatra, Raymundo Arroyave, Ruben Santamarta
|On-Site Speaker (Planned)
Ni-Ti-Hf high temperature shape memory alloys are extensively investigated because of their relatively high transformation temperatures and excellent mechanical properties. Chemistry and thermal processing tend to govern the transformation characteristics through the formation of so-called H-phase nano-precipitates and thus provide control on shape memory response. In the present work, we aim at understanding the role of chemistry and thermal processing on the transformation characteristics of a wide range of compositions, varying nickel from Ni=49.8% to Ni=51% and hafnium from Hf=5% to Hf=30%. In particular, we’ve revealed the role of Ni content on the transformation temperatures at different Hf contents. We’ve also studied the phase stability in the NiTiHf system at various temperatures, by constructing equilibrium ternary phase diagram isotherms with the help of diffusion multiple experiments. Knowledge of equilibrium phases at different temperatures aids in understanding the H-phase precipitate chemistry more clearly, which is important for developing predictive precipitate models.
||Planned: Supplemental Proceedings volume