Structure of medium-range order in molten Al-Fe alloy

摘要

The molecular-dynamics (MD) simulation was carried out to investigate the structure of medium-range order (MRO) of a liquid Al_5Fe_2 alloy. Prepeak is observed in the structure factor S(Q) , which is considered as the signature of MRO. Results from MD simulation and experiment agree well with each other, which proves reliability of the simulation. It is found from the calculated Ashcroft-Langreth structure factors that there exists strong interactional force between atom Al and Fe, which results in the great concentration fluctuation, i. e. the chemical order, in the liquid Al_5Fe_2. Both the chemical order parameter, α, and the Bhatis-Thornton(BT) structure factors indicate the preference for unlike-neighbor bonds. It is seen from the low-Q domain of S( Q) and the concentration-concentration structure factor S_(CC)(Q) that the prepeak mainly comes from the first peak of S_(CC) (Q). The structural model, which reflects the characteristic of MRO, is also constructed.