Solute segregation at the Al/η-MgZn₂ interface in Al-Zn-Mg-(Cu) alloys

The application of high-performance Al-Zn-Mg-(Cu) alloys at elevated temperatures remains constrained by the poor coarsening resistance of the strengthening η-MgZn₂ phase. Research indicates that solute segregation at η/Al interfaces can effectively enhance precipitate thermal stability by reducing interfacial energy and suppressing coarsening kinetics. To address this, this study employed high-throughput density functional theory calculations to systematically evaluate the segregation energies of 55 solute elements at conventional coherent and semi-coherent η/Al interfaces, while also computing their binding energies with Mg/Zn and their dissolution behavior within the η phase. Correlation analysis with 19 atomic descriptors reveals that interfacial segregation energy is synergistically governed by two dominant factors: (1) Atomic size effect—larger solute atoms preferentially segregate to relax interfacial strain; (2) Electronic interactions—particularly the selective bonding tendencies of solutes with second-nearest-neighbor Mg (2NN) and first-nearest-neighbor Zn (1NN). This work identifies that rare earth and specific post-transition metal elements exhibit unique capabilities for lowering interfacial energy. These findings provide a novel theoretical foundation and a feasible compositional design pathway for breaking the high-temperature performance limits of Al-Zn-Mg-(Cu) alloys through atomic-scale solute segregation engineering.