Atomic-Scale mechanisms of Lithium-Induced grain boundary embrittlement in aluminum alloys: A First-Principles study

GZ Feng and XS Kong and CS Zhang and GQ Zhao and L Chen, COMPUTATIONAL MATERIALS SCIENCE, 258, 114083 (2025).

DOI: 10.1016/j.commatsci.2025.114083

This study employs first-principles calculations to investigate the segregation of lithium (Li) at aluminum (Al) grain boundaries (GBs) and its influence on interfacial mechanical properties. Our results reveal that isolated Li atoms interact weakly with most GBs, with binding behavior strongly correlated to the local charge density distribution. As Li concentration increases, distinct clustering behaviors emerge: one-dimensional linear chains form along tilt axes at E5(310), E17(410), and E13(320) GBs, while a stable planar Li monolayer forms exclusively at the E5(210) GB. Li segregation weakens interfacial cohesion primarily by inducing localized electron depletion between neighboring Al atoms. The extent of Li segregation and its weakening effect varies across different GB types. Specifically, GBs, such as E5(210) and E43(335), are highly susceptible to embrittlement due to Li segregation, whereas other GBs, such as E3(112) and E17(223), show minimal or no effect on interfacial bonding strength. These atomistic insights inform a grain boundary engineering strategy that prioritizes the retention of Li- tolerant GB structures, while suppressing Li-sensitive configurations. This approach offers a roadmap for enhancing fracture resistance in Al- Li alloys without compromising their lightweight advantages.

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