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Chemo-mechanical modeling of dislocations in complex alloys

Wednesday (26.09.2018)
14:30 - 14:45 S1/01 - A4
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Dislocations and their interaction with precipitates and alloying chemistry is critical in the design of complex materials. In this work, atomistic phase-field microelasticity (APFM) [1, 2] is used to predict dislocation core structures. The results are compared directly with the molecular dynamics (MD) simulations for the model system of Ni-Ni3Al, and the formation of anti-phase boundary and complex stacking faults inside the Ni3Al precipitate are observed to be in good agreement with the MD results. Furthermore, the APFM is coupled with a thermodynamics-based model for solute transport, and the coupled dislocation-solute problem is benchmarked for the Ni-Al-Co system. In particular, the segregation of Co around the dislocation core inside the Ni3Al precipitate is investigated, where two types of segregation mechanisms are taken into account: the Cottrell atmosphere around the dislocation core, which is related to the hydrostatic stress field gradient; and Suzuki segregation, which is due to the change in the generalized staking fault energy surface with the solute concentration. A good qualitative comparison of the predicted defect structures is observed with experimental observations.


References:


[1] Mianroodi, J. R., & Svendsen, B., Atomistically determined phase-field modeling of dislocation dissociation, stacking fault formation, dislocation slip, and reactions in fcc systems. Journal of the Mechanics and Physics of Solids (2015), 77, 109-122.


[2] Mianroodi, J. R., Hunter, A., Beyerlein, I. J., & Svendsen, B., Theoretical and com- putational comparison of models for dislocation dissociation and stacking fault/core formation in fcc crystals. Journal of the Mechanics and Physics of Solids (2016), 95, 719-741.


[3] Purja Pun, G. P., & Mishin, Y., Development of an interatomic potential for the Ni-Al system. Philosophical Magazine (2009), 89(34-36).

Speaker:
Dr. Jaber Rezaei Mianroodi
Max-Planck-Institut für Eisenforschung GmbH
Additional Authors:
  • Paraskevas Kontis
    Max-Planck-Institut für Eisenforschung GmbH
  • Pratheek Shanthraj
    Max-Planck-Institut für Eisenforschung GmbH
  • Baptiste Gault
    Max-Planck-Institut für Eisenforschung GmbH
  • Bob Svendsen
    RWTH Aachen University