Dresden 2003 – wissenschaftliches Programm
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M: Metallphysik
M 23: Mechanische Eigenschaften IV
M 23.1: Vortrag
Dienstag, 25. März 2003, 16:30–16:45, IFW B
Softening of NIMONIC PE16 by precipitate free zones along grain boundaries — •Thorsten Krol and Eckhard Nembach — Institut für Materialphysik, Westfälische-Wilhelms-Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster
The reason for the good mechanical properties of many alloys is the precipitation of a second phase from the supersaturated state. In some of these alloys near the grain boundaries precipitation free zones (PFZ) are formed, which affect the mechanical properties. The aim of this work was to quantity the detrimental effects on the yield strength σy. The investigations have been performed for the nickel-based superalloy NIMONIC PE16, which was used as a well known model system for precipitation hardened materials forming PFZs.
The width of PFZs increases with the grain size. On the basis of the Hall-Petch relation a linear dependency of σy on d−1/2 (d= grain size) would be expected. Deviations from this dependency are due to the PFZs. They were found to lower σy by more than 20 percent. To understand the underlying dislocation mechanisms TEM-investigations were performed. The observed deviations could be attributed to the easy generation of dislocations in PFZs.