|About this Abstract
||2018 TMS Annual Meeting & Exhibition
||Computational Design and Simulation of Materials (CDSM 2018): Computational Design of Materials
||Calphad-type Assessment of the Ni-Ti-Hf System Combined with the DFT Calculations
||Chang-Seok Oh, Eun Ae Choi, Hak Sung Lee
|On-Site Speaker (Planned)
Stabilities of stable and metastable phases in the Ni-Ti-Hf ternary system have been critical issue in development of high temperature shape memory alloy, however, constitutional and thermo-chemical studies is still limited. In this study, thermodynamic assessment on the Ni-Ti-Hf ternary system was carried out based on the Calphad method combined with the first-principles calculation. The individual phases were described by the compound energy models and their Gibbs energy parameters were extended from binary systems reported elsewhere. In order to model ternary B2 phase being mainly responsible for shape memory effect, sub-lattice description of (Ni,Ti,Hf)(Ni,Ti,Hf) was adopted to keep consistency to previous assessments for low-order systems. Formation energies of the disordered phases and end-members of B2 phase derived from sub-lattice formalism were estimated by DFT supercell calculations. The ternary thermodynamic parameters were adjusted with available experimental data, and calculated phase equilibria for selected isopeth and isothermal sections are presented.
||Planned: Supplemental Proceedings volume