Atomistic details of metal additive manufacturing in powder beds

Selective laser sintering (SLS) has been successfully used to fabricate metal parts, but variability in mechanical performance due to microstructural defects (e.g. voids, cracks) has inhibited its widespread use. The ability to characterize and identify the origins of these defects in situ is highly desirable, with most efforts typically being restricted to destructive postmortem analysis. Atomistic simulations offer a method to explore defect nucleation during SLS. We employ non-equilibrium molecular dynamics to simulate a single pass of an energetic laser source in nanoscale powder beds. In metals, heat transport is dominated by electron mediated processes. As such, a multi-scale modeling approach is used, coupling an implicit representation of electronic processes to the atomic lattice phonon system. This talk will report on a series of simulations using this computational model to study the dynamics of melting and solidification of metal powders at the nanoscale. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.