Effects of Ce-doped on precipitation behavior of different nano-precipitates in Al–Li alloy and its benefits on mechanical properties

In this work, first-principles calculations were employed to construct interface models for three primary strengthening precipitates ((δ′, θ′, and T 1 ) in Al-Li alloys. The 2050 alloy doped 0.2wt% Ce was cast to validate the computational findings, aiming to reveal the influence of Ce on the phases interface characteristics and the corresponding strengthening mechanisms in Al-Li alloys. Ce exhibits selective doping behavior within the precipitates, preferentially substituting Li sites, which reduces the formation enthalpy of δ′ and T 1 phases while enhancing mechanical properties. For θ′ precipitate interface, Ce segregation is unfavorable. Nonetheless, Ce segregates at the Al/δ′/Al interface lowers interfacial energy and increases the separation work by 18%. At the Al/T 1 /Al interface, Ce segregation at Li sites strengthens interfacial bonding, whereas segregation at Al sites weakens the interface strength. Ce significantly refines the dendritic microstructure and modulates the type, size, and distribution of precipitates. The 0.2Ce-2050 alloy achieves a 10% and a 34.6% improvement in tensile strength and elongation, indicating a synergistic enhancement of strength and ductility.Aging kinetics analysis and TEM observations revealed that the precipitate nucleation rate in the 0.2Ce-2050 alloy is markedly accelerated relative to the 2050 alloy without Ce, meanwhile precipitates exhibiting smaller sizes and higher number densities. • The Ce atoms preferentially substitute Li sites in δ′ and T 1 phases, significantly reducing the formation enthalpy and enhancing thermodynamic stability. Concurrently, it forms robust Al-Ce bonds that strengthen interfacial bonding. • Experimental validation demonstrates that the 0.2Ce-2050 Al alloy achieves a 10% and a 34.6% improvement in tensile strength and elongation, indicating a synergistic enhancement of strength and ductility. • The Ce addition refines dendritic structures, reducing the average size of T 1 precipitates from 250 nm to 180 nm while increasing their number density. • Precipitation kinetics analysis reveals that Ce accelerates the peak aging process, shortens thermal processing cycles.