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L.C. Whitmore, H. Leitner, E. Povoden-Karadeniz, R. Radis, M. Stockinger et al.:
"Transmission electron microscopy of single and double aged 718Plus superalloy";
Materials Science and Engineering A, 534 (2012), 413 - 423.

The effects of single and double aging upon the ATI 718Plus Nickel superalloy are investigated. Double
aging is found to produce an increase in hardness as compared to single aging, thus an extensive microstructural
study is performed to identify and understand the physical reasons for this. Precipitation of the
phase is of particular interest in this case. Using transmission electron microscopy and energy dispersive
X-ray spectroscopy, the shape, size, number density and elemental constitution are investigated
and correlated to the aging conditions. The / lattice misfit is also measured. Only one main population
of precipitates is observed after double aging: simply the population produced during the first aging
continues to evolve. Using a theoretical model for precipitation hardening, based on the shearing of precipitates,
the hardness is related to the size and phase fraction of the and a value for the anti-phase
boundary energy of the is calculated. Measurements are compared with thermo-kinetic simulation
using the software package MatCalc. A dense dispersion of 1-2 nm size phase clusters is additionally
observed after both single and double aging, and this is correlated through simulation with the final
cooling stage of the heat treatment.
© 2011 Elsevier B.V. All rights reserved

718Plus Superalloy Gamma-prime Precipitation hardening Transmission electron microscopy Anti-phase boundary energy

http://dx.doi.org/10.1016/j.msea.2011.11.089