Methods of segregation analysis applied to simulated multicomponent multiphase microstructures

Abstract

Advanced microstructure simulation models can predict solute segregation in 2D and 3D space, which often leads to outputs of large arrays of concentration values with a multitude of detailed information that hinders straightforward evaluations. The target of this study is to establish a common evaluation method for both simulation results and experimental data as a standard for quantitative comparison and validation. For this purpose, a methodology is adopted from experimental segregation analysis to transform the multi-dimensional data into meaningful 1D segregation profiles, which can easily be plotted and discussed. As an application example, a directional solidification experiment on an AZ31 magnesium alloy is selected and the solidification process is simulated using the phase-field method. The subsequently obtained 1D segregation profiles are compared to measured segregation profiles. As part of the study, two common sorting methods are evaluated with respect to their applicability to recover the general segregation behavior and the solidification path, as well as to handle numerical noise.

3D phase-field computations of microsegregation in nodular cast iron compared to experimental data and Calphad-based Scheil-prediction

“…A changing curve progression generally requires a different sorting of the simulation data e.g. with respect to a leading element or a weighted rank number [7] . As a consequence of the simplified sorting, we observe a small, however almost negligible, deviation from Scheil in the very first part of the simulated distribution curve in Fig.…”

“…The coupling to thermodynamic databases enables handling of complex multicomponent multiphase quasi-equilibria, while diffusion matrixes can consistently be derived from mobility databases. Calphad-coupled MMPF simulations have become state of the art for steels [ 3 , 4] and many other technical alloys [5][6][7] , however not yet for alloys that exhibit significant volume change during solidification. This is especially true for nodular cast irons where graphite forms in a divorced eutectic transformation, with graphite expanding upon crystallization while austenite is shrinking.…”