耦合CALPHAD的微观相场中Ni-Al与Ni-Si合金原子时效模拟

Simulation of Atomic Aging Process of Ni-Al and Ni-Si Alloys in Microscopic Phase Field by Coupling CALPHAD

通过结合微观相场及计算相图方法,拟合得到L12结构中第一、第二近邻原子间交互作用能,进而模拟了Ni-Al、Ni-Si二元合金在γ→γ'相变过程中的合金原子簇聚及有序化行为。模拟结果得出,当Al或Si的原子分数为17.5%时,随着时效温度的升高,L1_2相析出孕育期更长;同时,有序化总是先于溶质原子的簇聚,形成非化学计量比有序相;借助计算相图,可将微观相场方法应用于更多二元体系的γ→γ'型相变研究。

The 1 stand 2 ndnearest neighbor effective interchange interaction energies in L12 structure were obtained by combining microscopic phase field and calculation of phase diagrams,and the ordering and clustering process of the alloy in the γ → γ’ transition of Ni-Al and Ni-Si binary alloys was simulated. The simulation results showed that when the atomic fraction of Al or Si was 17. 5%,with the aging temperature increasing,the incubation period of L12 precipitation was longer;the ordering was always prior to solute atoms clustering,and the non-stoichiometric order phase was formed. The microscope phase field method could be applied to the research of γ → γ’ type phase transition of the binary system by calculation of phase diagrams.