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Abstract: The effect of Fe content on atomic site occupation in L12–Ni3(Al1− x Fe x ) structure at 1073 K was studied by using microscopic phase-field model. The results show that with increasing Fe, Fe atoms prefer to occupy the Al sites (β sites), and the site occupation probability (SOP) gradually increases, while the SOP of Al atoms on β sites decreases accordingly. Meanwhile, a small amount of Ni atoms also occupy β sites which is the so-called anti-site behavior; reversely, such behavior happens as a trace amount of Al and Fe atoms occupies α sites. Unlike Ni atoms, the anti-site behavior of Al and Fe atoms is strengthened with the increase of Fe content. Further, the precipitation mechanism, the size and the ordering degree of L12 structure also present obvious changes with the addition of Fe. [Copyright &y& Elsevier]