An approach to regulating grain boundary network by introducing high fraction of ∑3n and serrated grain boundaries simultaneously in Fe-Ni based alloy

Abstract

• A method for further optimization of GB character distribution in Fe-Ni based alloy is proposed. • Both high fraction of ∑3 n boundaries and SGBs can be introduced in Fe-Ni based alloy simultaneously. • The fraction of special triple junctions is further increased. • The formation of SGBs is associated with the preferential growth of γ′ precipitates towards the RGBs. Random grain boundaries (RGBs) as weak links has closely related to the initiation and propagation of cracks in intergranular corrosion, stress corrosion and hydrogen embrittlement, etc. Hence, Grain boundary engineering (GBE) is proposed which manipulates GB structure by introducing ∑3 n boundaries and disruption RGBs network to optimize materials properties. However, GBE is insufficient to optimize the whole grain boundary structure as theoretical maximum fraction of ∑3 n boundaries. In this paper, an approach is proposed which optimize the microstructure in Fe-Ni based alloy by increasing ∑3 n boundaries also simultaneously changing some of the rest RGBs into serrated grain boundaries (SGBs). Moreover, the formation mechanism of SGB in Fe-Ni based alloy is also clarified.