First-principles calculations of co-segregation behavior of transition metal solutes and hydrogen along aluminum grain boundaries

In the realm of aluminum and its alloys, the susceptibility to stress corrosion during applications is often attributed to the segregation of hydrogen atoms at grain boundaries. This article is dedicated to examining the co-segregation behavior of solute atoms in conjunction with hydrogen atoms at three specific grain boundaries (Σ5 (2 1 0), Σ11 (1 1 3), Σ3 (1 1 1)). The research employs first-principles methods, using aluminum as the substrate, with a specific emphasis on choosing 3d and 4d transition metals as solute atoms. The study unveils that the co-segregation energy is intricately influenced by the distinct segregation behaviors of solute atoms and their interactions with hydrogen atoms. Notably, a stronger tendency of solute atoms to segregate, coupled with heightened solute-hydrogen attraction, amplifies the likelihood of their co-segregation. Furthermore, the interactions between different solute atoms are influenced by the combined effects of elastic interactions and charge interactions. Collectively, this research provides deep insights into the co-segregation at grain boundaries.