Molecular dynamics simulations of nanoscale solidification in the context of Ni additive manufacturing

Solidification is a key step in additive manufacturing technology because it determines the microstructure and performance of final product. Our work provides nanoscale description relevant solidification processes for polycrystalline Ni by means molecular dynamics simulations. In particular, we focus on thermal effects associated with characteristic non-stationary conditions manufacturing. Directional homogeneous nucleation are investigated as function operating parameters that control temperature gradient cooling rate. We show planar solid/liquid interface propagates at constant speed, presence between melt pool solidified region. By adding to pool, columnar-to-equiaxed transition can be captured nanoscale. If undercooling not sufficient promote nucleation, strong instability develops, forming protusions. The behaviors observed interpreted terms classical theories nucleation.