[SY-F7] Symposium F-7

[SY-F7] Phase-field modeling of precipitation growth and ripening during heat-treatment conditions in Ni-base superalloys

^○Michael Fleck, Felix Schleifer, Markus Holzinger, Yueh-Yu Lin, Uwe Glatzel (Metals and Alloys, University Bayreuth, Germany)

We develop a phase-field model for the simulation of chemical diffusion limited microstructure evolution, with a special focus on precipitation growth and ripening in multi-component alloys. Further, the model accounts for elastic effects, which result from the lattice-misfit between the precipitate particles and the parent matrix-phase. To be able to simulate particle growth and ripening in one dimension, we introduce an extra optional driving-force term, which mimics the effect of the curved particle/matrix interface in one dimension. As a case study, we consider the gamma'-precipitation growth and ripening under the influence of realistic heat treatment time-scales in the multi-component Ni-base single crystalline cast alloy CMSX-4. The respectively required temperature-dependent thermodynamic and kinetic input parameters are obtained from CALPHAD calculations using the commercial software-package ThermoCalc. The required temperature-dependent elastic parameters are measured in-house at the chair of Metals and Alloys, using resonance ultrasound spectroscopy for the anisotropic and inhomogeneous stiffness-tensor and high temperature X-ray defraction for the lattice misfit.
We study the kinetics of growth and ripening of statistically many interacting precipitated particles as function of the temperature and time in one and two dimensions, with the explicit consideration of up to 8 independent chemical components. Furthermore, the model is applied to calculate the detailed shape-evolution of a few interacting gamma'-particles in two and three dimensions with periodic boundary conditions. Relations to the shapes of gamma'-particles in respectively heat treated experimental microstructures are discussed.