Berlin 2018 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 3: Crystal Structure, Defects, Real Structure and Microstructure in Materials
KFM 3.8: Vortrag
Montag, 12. März 2018, 12:10–12:30, E 124
Coarsening and growth of metastable γ ″ precipitates in Ni-based superalloys — •Felix Schleifer, Markus Holzinger, Yueh-Yu Lin, Michael Fleck, and Uwe Glatzel — Metals and Alloys, University of Bayreuth, Germany
We develop a phase field model for the simulation of diffusion-limited precipitation in Ni-based superalloys with industry-relevant chemical complexity. In the wrought alloy Inconel 718 superior performance at high temperatures is achieved by coherent γ ″ precipitations in the fcc matrix. Under non-equilibrium conditions the metastable Ni3Nb intermetallic compound γ ″ with tetragonal structure is the main strengthening phase in the alloy. During heat treatment and aging the formation and coarsening of such precipitates is controlled by Nb-diffusion in the matrix.
The thermodynamic formulation of the model will be validated by comparison to respective CALPHAD equilibrium calculations using the commercial software ThermoCalc. Furthermore, an elastic term is included in the model to account for external loads, anisotropic lattice mismatch stresses as well as elastic inhomogeneities between the considered phases.
This project was recently started as part of the second phase of the DFG priority program 1713. We aim to study steady state growth and coarsening of the precipitated particles as a function of the basic two heat treatment parameters i. e. temperature and time. Phase field studies concerning multiple particles and microstructure evolution under mechanical loading will be carried out subsequently.