Structure and Stability of the Stoichiometric Al3Fe Phase

Abstract

A disordered stoichiometric Al3Fe phase was obtained when synthesizing Al8Fe3 by the spark plasma sintering (SPS) approach and its crystal structure was determined by the single-crystal X-ray diffraction (SXRD) techniques. The refined structure is an isotype of the reported Al5Fe2 phase, only different in the site occupation factors (s. o. f.) of Al2 and Al3 atoms, which was refined to be 0.431 (13) and 0.569 (13), respectively. Stimulated by the structural refinement results, an ordered stoichiometric Al3Fe phase was established. First-principles calculations reveal that the ordered Al3Fe phase is mechanically and dynamically stable and has a much lower value of enthalpy of formation than any other proposed Al3Fe phases, although it is also metallic and metastable.

Characterization of the Convoluted 3D Intermetallic Phases in a Recycled Al Alloy by Synchrotron X-ray Tomography and Machine Learning

“…Al3Fe or Al13Fe4 are the common equilibrium phases in the Al-Fe binary system, which has a larger unit cell parameter (C2/m space group). In the Al-Fe-Si system, Al3Fe is easy to form when the cooling rate is low, and the Fe/Si ratio is high [27][28]. The crystal structure of the Al3Fe phases also makes them easy to develop into platelet-like spatial network structures [29].…”