Title: 3D Phase-field Simulations of Sintering and Coarsening in Polycrystalline Multi-phase Materials
Other Titles: 3D faseveldsimulaties van sinteren en vergroving in polykristallijne multi-fase materialen
Authors: Ravash, Hamed
Issue Date: 10-Dec-2014
Abstract: An appropriate multi-phase multi-component phase-field model was developed. The accuracy of the developed model was verified by implementing the model for small scale systems in 2-D using MATLAB. In order to perform 3-D large scale simulations, an advanced implementation method called Bounding-box algorithm was developed using C++ object-oriented programming language. The advanced implementation offered faster calculation and lower storage requirement. The developed software was used to study the effect of interfacial energy and diffusivity of elements on the evolving microstructures in three solid phase systems and the effect of solid volume fraction and interfacial energy in two phase solid-liquid systems. In order to verify the simulation results, the microstructural features of a liquid phase sintered NbC-Co cermet were measured in 2-D and 3-D using the 2-D and 3-D Electron Backscattered Diffraction method. The obtained results were compared with the simulation results. For three solid phase systems, depending on the interface energy between grains of the same phase and grains of dissimilar phases, different phase arrangements resulted. For all cases, a growth rate exponent of n = 3 was measured implying long range diffusion controlled growth. The growth rate of each phase was found to be a function of the diffusivities of the elements and the phase arrangement. In all cases, the phase with the lowest diffusivity was the fastest growing and shows the highest number of faces. For two phase solid-liquid systems, the growth rate, shape and number of particle-particle contacts were found to be a function of the interface energy between solid particles and liquid phase. With increasing particle-particle contacts, the growth rate exponent decreased indicating a change in the coarsening mechanism from Ostwald ripening to grain growth. The mean dihedral angle was measured using contiguity and connectivity measurements. The measured microstructural features from the EBSD measurements agreed well with the simulation results.
Publication status: published
KU Leuven publication type: TH
Appears in Collections:Sustainable Metals Processing and Recycling
Surface and Interface Engineered Materials

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