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E. Povoden-Karadeniz, M. Kozeschnik, T. Wojcik, E. Kozeschnik:
"Investigation of γ´ precipitation in Ni-base superalloy PWA1480";
Talk: 5th ASEM Workshop "Advanced Electron Microscopy", MedUni Graz; 2015-05-07 - 2015-05-08.

Interrupted cooling experiments are capable of discovering the start temperature of the earliest stages of precipitation. With this method, the start temperature of γ´ precipitation in single crystal Ni-base superalloy PWA1480 was determined inside 5 K. Solution-treated specimens were cooled stepwise to different temperatures above and below the estimated temperature, where nucleation of γ´ occurred first. The microstructures resulting from these cooling experiments were explored by transmission electron microscopy. This (Ni,Co)3(Al,Ti) hardening phase is coherent with the matrix and was investigated using dark field imaging. Development from initially cuboid, diffuse particles via octo-cubes towards octo-dendrites was shown as a function of interrupting temperature. Differential scanning calorimetry, prior to the interrupted cooling experiments, was used to identify the temperature range of the main event of γ´ formation. The experimental heat flow, as well as particle size and distribution showed a good agreement with thermo-kinetic precipitation simulations.