Numerical simulation of microstructure evolution during laser directed energy deposition for Inconel 718 using cellular automaton method coupled with Eulerian multiphase

•A multi-scale cellular automaton-Eulerian multiphase model is employed to predict the microstructure during the laser directed energy deposition of Inconel 718.•The evolution of grain structure and dendritic structure during the solidification of the whole melt pool is realized.•A complex microstructure evolution mechanism including the epitaxial growth of dendrites from the substrate, heterogeneous nucleation, competitive growth between epitaxial columnar grains, nucleated columnar grains and equiaxed grains was presented.