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The suitability of the phase field method for the simulation of the evolution of the microstructure during sintering, which has been assumed for more than a decade, receives new impetus from the progress described in this paper. A zero force formulation for the calculation of the rigid body motion of powder particles is adapted to diffuse interface model of Cahn–Hilliard and Allen–Cahn type. In this approach, the rigid body motion ensures the mechanical equilibrium in the powder compound. For this aim, the derivative of the free energy with respect to the additional degree of freedom of rigid body motion was approximated by a force in the grain boundary caused by concentration differences there. The potential of the model is demonstrated by first 2D simulations. These are compared with 2D simulations results generated with a model, which previously showed good agreement with experimentally obtained sintering data in the 3D case. In this comparison good agreements are observed qualitatively as well as quantitatively, showing the plausibility of the new approach.

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A novel discrete element method-based approach for modeling of solid state sintering of spherical metallic powder is presented. It tackles the interplay between the thermodynamical mass transport effects arising in the vicinity of the grain boundary between the particles and their mechanical interaction. To deal with the former, an elementary model is used that describes the behavior of the matter flow at the grain boundary such that neck growth and shrinkage are properly captured. The model solves a set of partial differential equations which drive the changes of the corresponding geometry parameters. Their evolution is transformed into the equivalent normal sintering force arising in each sinter neck. To capture the mechanical interaction of particles due to their rearrangement resulting from the geometry changes of each individual contact, the entire assembly is modeled as an assembly of 2-nodal structural elements with 6 degrees of freedom per node. The stiffness properties are estimated employing the approximations from the bonded DEM. The numerical implementation then constitutes a two-step staggered solution scheme, where these models are applied sequentially. The performed benchmarks reveal the plausibility of the proposed approach and exhibit good agreement of both neck growth and shrinkage rates obtained in the numerical simulations with the experimental data.