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arXiv · 1407.5013

Crystal structure, thermodynamics, magnetics and disorder properties of Be-Fe-Al intermetallics

Patrick A. Burr·Simon C. Middleburgh·Robin W. Grimes
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Abstract

The elastic and magnetic properties, thermodynamical stability, deviation from stoichiometry and order/disorder transformations of phases that are relevant to Be alloys were investigated using density functional theory simulations coupled with phonon density of states calculations to capture temperature effects. A novel structure and composition were identified for the Be-Fe binary {\epsilon} phase. In absence of Al, FeBe_5 is predicted to form at equilibrium above ~ 1250 K, while the {\epsilon} phase is stable only below ~ 1650 K, and FeBe_2 is stable at all temperatures below melting. Small additions of Al are found to stabilise FeBe_5 over FeBe_2 and {\epsilon}, while at high Al content, AlFeBe_4 is predicted to form. Deviations from stoichiometric compositions are also considered and found to be important in the case of FeBe_5 and {\epsilon}. The propensity for disordered vs ordered structures is also important for AlFeBe_4 (which exhibits complete Al-Fe disordered at all temperatures) and FeBe_5 (which exhibits an order-disorder transition at ~ 950 K).

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Patrick A. Burr, Simon C. Middleburgh, Robin W. Grimes. 2014-07-18. Crystal structure, thermodynamics, magnetics and disorder properties of Be-Fe-Al intermetallics. https://doi.org/10.1016/j.jallcom.2015.03.101

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