Boride-induced dislocation channeling in a single crystal Ni-based superalloy

Generally, minor elements such as carbon and boron are added in superalloys to strengthen grain boundaries. However, effects of carbon and boron on single crystal superalloys remain disputed. Here we demonstrate that M23B6 (where M is mixture of W, Mo, Cr and Ni) can induce dislocation channeling in a Ni-based single crystal superalloy. The M23B6 has a cube-on-cube orientation relationship with the matrix, forming a majority of {1 1 1} plane interfaces. Furthermore, the atomic stepped {1 1 1} interface could facilitate dislocation nucleation. Dislocations emitted from the interface glide forward and pile-up in the channel, resulting in strain localization and creep micro-crack initiation. (C) 2018 Elsevier B.V. All rights reserved.