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M.R. Ahmadi, A. Falahati, E. Kozeschnik:
"A model for precipitation strengthening in multi-particle systems";
Talk: 17th International Conference on the Strength of Materials (ICSMA 17), Brno (invited); 2015-08-09 - 2015-08-14.

In recent years, we have developed a consistent model describing the increase of yield strength caused by precipitation of second phase particles. The model accounts for shearing and non-shearing mechanisms, depending on the coherency between precipitates and matrix as well as strength contributions from the various strengthening mechanisms. The physical key parameters entering the model are critically evaluated on basis of the dislocation line tension, free distance between particles and precipitate radius. A set of equations is derived, which describes the yield strength increase due to the interaction between dislocations and precipitates. Based on coupling equations for the individual strengthening mechanisms, the model allows for a predictive simulation of the final yield strength caused by precipitation in multi-particle, multi-phase systems. With the aid of contemporary computational power, the enhanced strengthening equations deliver more accurate results compared to the conventional equations that involve several simplifications and approximations that are often not representative for the precipitation system under consideration. Application of the model is demonstrated on the example of precipitation strengthening in the Ni-base superalloy 718.