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T. Wojcik, M. Rath, E. Kozeschnik:
"TEM-Characterization and Precipitation Simulation of Secondary Phases in Ni-base Superalloy Rene 65";
Talk: EUROMAT 2017, THESSALONIKI; 2017-09-17 - 2017-09-22.

The Ni-base superalloy Rene 65 is a newly introduced cast and wrought alloy, used for turbine disk applications in aero-engines. The fine-grained and γ´-strengthened alloy was developed to increase service temperatures up to over 700°C and therefore, enhance the efficiency of aero-space turbines.
In this work, the secondary phases occurring in the as-received material as well as in different heat treatment conditions are characterized by transmission electron microscopy (TEM). In the as-received material condition, a tri-modal γ´ size distribution is found ranging from a few nanometers up to approx. 5 µm. In addition, borides are found preferable at grain boundaries with a size of approx. 1 µm. The boride phases could be identified by means of energy-dispersive X-ray spectroscopy (EDX), electron energy loss spectrometry (EELS) with selected area electron diffraction (SAED) as tetragonal M3B2 and M5B3, respectively, with Cr and Mo as the main metallic constituents. For different cooling rates, a change in the morphology and size distribution of the γ´ precipitates is found. These results are compared with thermo-kinetic precipitation simulations using the MatCalc software package.