INTERFACES IN A MODIFIED INCONEL-718 WITH COMPACT PRECIPITATES

Interfaces in a modified Inconel 718 containing compact precipitates w ere investigated using high resolution transmission electron microscop y. Morphology configuration and crystallography of the compact precipi tate were confirmed as cube-shaped gamma' precipitate and ail six face s were coated with a thin shell, these shells could be classified as t hree variants of disc-shaped gamma '' precipitates on {001} planes of the matrix, and the [001] orientations (c-axis) of the three variants of gamma '' precipitate shells were parallel to [001], [010] and [100] orientations of the matrix. The interfaces of gamma '' precipitate/ma trix, gamma' precipitate/matrix, and gamma '' precipitate/gamma' preci pitate were fully cube-cube coherent, and the atoms at both sides of t he interfaces maintained a perfect match with no disordered structure transition region. It was suggested that the higher thermal stability of the modified Inconel 718 alloy than that of conventional Inconel 71 8 alloy was due to the morphology configuration of the compact precipi tate and fully coherent interfaces among the gamma' precipitate, gamma '' precipitate and matrix. (C) 1997 Acta Metlallurgica Inc.