Effects of a vacancy, Cr and Mo on the electronic structure of FeAlΣ3 [111] grain boundaries

Abstract

The preferred positions of a vacancy and Cr or Mo alloying elements on FeAlΣ3 [111] grain boundaries are investigated, and the effects of the vacancy or different concentrations of Cr or Mo on the formation energy, cohesive energy, strengthening effect and electronic structure of this grain boundary are analyzed using first principles based on density functional theory. The vacancy easily forms at the Fe site and weakens the interface. At different concentrations, Cr or Mo is segregated in the FeAlΣ3 [111] grain boundary in a stable configuration, and both preferentially replace Al atomic positions. Both Cr and Mo strengthened the FeAl grain boundary, and the strengthening effects can be attributed to the fact that Cr or Mo addition causes Cr-d or Mo-d orbital electrons to be involved in a hybrid orbital at the FeAl grain boundary. This increases the charge density of the grain boundary, strengthening the atomic binding capacities of the FeAl grain boundaries.