Experimental and first-principles characterization of T(Al20Cu2Mn3) phase interfacial segregation behavior in Al-Cu-Mg alloys

In this work, the segregation behavior of atoms at the T/Al interface is systematically analyzed by transmission electron microscopy and first-principles calculations. The atoms segregating to the vicinity of the T-phase interface are mainly Cu and Mg, and it is found that Cu has a strong tendency to replace the Al atoms at the interface, whereas Mg segregates almost exclusively to the vacancies between the atoms. Calculations of bulk phases and interfaces predict possible types and effects of solute segregation. After the co-segregation of solutes Cu and Mg, the CuMg-terminated are the most thermodynamically stable in terms of energy, virtually in agreement with the experimental observations. These efforts provide fundamental simulation data to study the segregation behavior at the T/Al interface and also give the necessary help for experimental characterization from an energetic point of view.