ICAMS / Interdisciplinary Centre for Advanced Materials Simulation
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Influence of misfit stresses on dislocation glide in single crystal superalloys: A three-dimensional discrete dislocation dynamics study

Date: 12.05.2015
Time: 12:00
Place: 12th International Conference on the Mechanical Behavior of Materials, Karlsruhe, Germany

Siwen Gao
Marc Fivel, Science et Ingénierie des Matériaux et Procédés, Université Grenoble Alpes, St Martin d'Heres, France
Alexander Hartmaier

Ni-base (or Co-base) single crystal superalloys are mainly applied as turbine blades in the hottest regions of gas turbines, due to their outstanding creep deformation resistance. In the characteristic γ/γ’ microstructure of single crystal superalloys, the lattice mismatch of these two phases results in a significant misfit stress field, which plays a decisive role for the micromechanical processes which lead to the observed macroscopic athermal deformation behavior of these high-temperature alloys. The sign and magnitude of this lattice mismatch depend on the chemical composition of materials as well as on the temperature. All currently used Ni-base superalloys possess a negative lattice misfit that becomes more negative with increasing temperature, while recently developed Co-base superalloys with a similar γ/γ’ microstructure have a positive lattice mismatch that decreases at higher temperatures.

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