Phase-field simulations and microstructural analysis of epitaxial growth during rapid solidification of additively manufactured AlSi10Mg alloy

In metal additive manufacturing, the unique microstructure from extreme process conditions determines the properties of the build part. In this study, the microstructural evolution of the additively manufactured AlSi10Mg alloy was studied to elucidate the relationship between its growth morphology and the local thermal gradient during rapid solidification. The microstructure of a uniaxially built specimen, as analyzed by electron backscatter diffraction (EBSD), exhibiting the [100](001) texture along the building direction. To investigate the local growth morphology, phase-field simulations were performed to examine the effect of grain misorientation on the previously built layer with respect to the thermal gradient direction. Furthermore, the solidification of partially melted microstructures observed during the EBSD measurements was simulated under the rapid solidification conditions. The obtained results revealed that the growth morphology of alloy grains during solidification strongly depended on the misorientation angle of the previously built layer measured with respect to the local thermal gradient direction. The simulated microstructures were in good agreement with the experimentally observed alloy morphology, which indicated that the utilized phase-field method could be potentially used in quantitative microstructural modeling. [Display omitted] •Phase-field simulations and EBSD analysis are performed to study the epitaxial growth in an additively manufactured alloy microstructure.•Solidification microstructure grows epitaxially on the surface of partially melted, previously deposited layer.•A relationship between the solidification growth morphology and the local thermal gradient is established.