First-Principles Insights into Metallic Doping Effects on Yttrium {10-10} Grain Boundary

Abstract: Yttrium and its alloys are promising materials for high-tech applications, particularly in aerospace and nuclear reactors. The doping of metallic elements at grain boundaries can significantly influence the stability, strength, and mechanical properties of these materials; however, studies on solute segregation effects in Y-based alloys remain scarce. To address this gap, we employs first-principles calculations to systematically examine the effects of doping with 34 metallic elements on the properties of a highly symmetric twin grain boundary in yttrium. All solute elements exhibit a tendency to segregate to regions near the grain boundary, driven by segregation energy.energy barriers influence these elements to prefer segregation positions farther from the grain boundary line. the strengthening energy calculations reveal that all dopant elements enhance grain boundary strength when located near the boundary. For grain boundary energy and solubility trends, elements within the same transition metal group across different periods display consistent behaviors. And considering grain boundary energy effects, we identify 11 elements (Al, Zn, Rh, Pd, Ag, Cd, Sn, Ir, Pt, Au, Hg) that preferentially segregate near the grain boundary, where they contribute to grain boundary strengthening and enhanced stability. By decomposing the strengthening energy into mechanical, chemical, and vacancy formation components, chemical contribution is the primary factor in strengthening, while the mechanical contribution of transition metals correlates with changes in the Voronoi volume and relative atomic radius of the solute. The density of states analysis indicates that increased grain boundary stability arises mainly from hybridization between solute d orbitals and yttrium, leading to more stable electronic states. This study provides theoretical guidance for optimizing metallic dopants in Y-based alloys.