M5B3 Boride at the Grain Boundary of a Nickel-based Superalloy

摘要

The grain boundary microstructures of a heat-treated Ni-based cast superalloy IN792 were investigated. The results show that M_5B_3 boride precipitates at the grain boundary. A special orientation relationship between M_5B_3 phase and the matrix at one side of the grain boundary is found. At the same time, two M_5B_3 borides with different orientations could co-exist in a single M_5B_3 particle as an intergrowth besides existing alone, thus forming orientation relationship between the two M_5B_3 phases and matrix. This phenomenon could be attributed to the special orientation relationship between M_5B_3 phase and the matrix.