Magnetochemical effects on phase stability and vacancy formation in fcc Fe-Ni alloys

Article

关键词: ORDER-DISORDER TRANSITION;    CENTERED-CUBIC IRON;    POSITRON-ANNIHILATION;    DECOMPOSITION KINETICS;    SELF-DIFFUSION;    NICKEL;    INVAR;    DYNAMICS;    DEFECTS;    ENERGY;   

DOI  :  10.1103/PhysRevB.106.024106

来源: SCIE

【 摘 要 】

We investigate phase stability and vacancy formation in fcc Fe-Ni alloys over a broad composition-temperature range, via a density functional theory parametrized effective interaction model, which includes explicitly spin and chemical variables. On-lattice Monte Carlo simulations based on this model are used to predict the tem-perature evolution of the magnetochemical phase. The experimental composition-dependent Curie and chemical order-disorder transition temperatures are successfully predicted. We point out a significant effect of chemical and magnetic orders on the magnetic and chemical transitions, respectively. The resulting phase diagram shows a magnetically driven phase separation around 10???40% Ni and 570???700 K, between ferromagnetic and paramagnetic solid solutions, in agreement with experimental observations. We compute vacancy formation magnetic free energy as a function of temperature and alloy composition. We identify opposite magnetic and chemical disordering effects on vacancy formation in the alloys with 50% and 75% Ni. We find that thermal magnetic effects on vacancy formation are much larger in concentrated Fe-Ni alloys than in fcc Fe and Ni due to a stronger magnetic interaction.

【 授权许可】

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