From Northwestern University Center for Atom-Probe Tomography
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APT image

Within a model Ni-5.2 Al-14.2 Cr at. % superalloy, γ'-precipitation is first detected with atom-probe tomography (APT) after aging for 600 s at 873 K. Each dot within this thin 12 x 5 x 2 nm3 slice from an APT reconstructed volume represents an atom, positioned with sub-nanometer sensitivity, from a specimen aged at 600 s and analyzed along the [001]-direction. The Al and Cr atoms, displayed with red and blue dots, are enlarged in the nanometer-sized γ'-precipitate (R = 0.8 nm) to emphasize the resolution of {002} superlattice planes (d200=0.356 nm) associated with the L12-ordered γ'-phase. The interface between the γ'-precipitate and γ-matrix is delineated clearly with a red 9 at. % Al isoconcentration surface. Approximately, 2/3 of the γ'-precipitate volume is imaged above, and the full precipitate contains 109 detected atoms: 78 Ni (not displayed), 21 Al, and 10 Cr.