Ageing process of pre-precipitation phase in Ni0.75Al0.05Fe0.2 alloy
based on phase field method
based on phase field method
(1. College of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China;
2. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China)
2. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China)
Abstract: By utilizing phase field method combined with analysis on free energy and interatomic potentials, pre-precipitation phase formation and transformation process of Ni0.75Al0.05Fe0.2 alloy in early precipitation stage during the ageing process under 1 000 K were studied. And free energy, microstructures, compositions and volume fractions of pre-precipitation phase and equilibrium phase were analyzed. The simulation results indicate that nonstoichiometric L10 pre-precipitation phase formed first, and then would gradually transform into L12 equilibrium phase. It is discovered that the phase transformation process was closely related to free energy and interatomic potentials. Additionally, it is revealed that free energy of L10 pre-precipitation phase was higher and interatomic potential was smaller than that of L12 equilibrium phase. Therefore, it is concluded that L10 phase was unstable, and phase transformation would occur to L12 which was more stable.
Key words: pre-precipitation phase; equilibrium phase; interatomic potentials; free energy; phase field method