Phase-field study of spinodal decomposition under effect of grain boundary* *Project supported by the National Natural Science Foundation of China (Grant No. 51801154), the Fund from the State Key Laboratory of Solidification Processing in Northwestern Polytechnical University, China (Grant No. SKLSP201813), and the Shaanxi Provincial Science Fund for Distinguished Young Scholars, China (Grant No. 2018JC-027).

Abstract

Grain boundary directed spinodal decomposition has a substantial effect on the microstructure evolution and properties of polycrystalline alloys. The morphological selection mechanism of spinodal decomposition at grain boundaries is a major challenge to reveal, and remains elusive so far. In this work, the effect of grain boundaries on spinodal decomposition is investigated by using the phase-field model. The simulation results indicate that the spinodal morphology at the grain boundary is anisotropic bicontinuous microstructures different from the isotropic continuous microstructures of spinodal decomposition in the bulk phase. Moreover, at grain boundaries with higher energy, the decomposed phases are alternating α/β layers that are parallel to the grain boundary. On the contrary, alternating α/β layers are perpendicular to the grain boundary.