Atom probe analysis of the compositions of (gamma)(prime) and (gamma)(double prime) intermetallic phases in nickel-based superalloy 718.

摘要

An atom probe field ion microscopy and transmission electron microscopy characterization has been performed on the intragranular precipitates that are formed in a niobium-modified nickel-base superalloy 718 after the various stages of a multistage heat treatment. Atom probe results indicate that there is a wide variation in the compositions of the DO(sub 22)-ordered (gamma)(double prime), the Ll(sub 2)-ordered (gamma)(prime) precipitates and the (gamma) matrix with heat treatment and with position in the microstructure. 7 refs., 4 figs., 7 tabs.