Elements segregation and phase precipitation behavior at grain boundary in a Ni-Cr-W based superalloy

In this work, grain boundary (GB) carbides and GB segregation are investigated on the basis of GB characteristics. The M23C6-type carbides are found to be the dominant GB carbides. GB M23C6 carbides prefer to precipitate at the general high-angle grain boundaries (HAGBs), while the Σ3 coherent twin boundaries with low interfacial energy are generally immune to precipitate M23C6. Correspondingly, a distinct segregation is observed at general HAGBs, and unobvious segregation is detected at Σ3 coherent twin boundaries. Combined with GB segregation and orientation relationship (OR) between GB M23C6 and γ matrix, the precipitation mechanism of GB M23C6 is proposed.