External electric field-induced melt deformations in laser-directed powder processing

External electrical fields (EFs) provide a unique strategy to manipulate fluid deformations independently of thermal parameters. This offers a unique opportunity in laser processes involving melting, where melt pool responses can be complex. Here, we explore the effects of non-contact EFs during laser processing of stainless steel. Metal powder is locally melted and resolidified under a constant laser energy input in the presence of various EFs. Both constant and time-varying EFs induce significant changes upon resolidification, transforming naturally spherical droplets into anisotropic oblate melt geometries aligned with the applied field. Calculations indicate EFs alter surface tension, leading to changes in the wetting behavior of the melt. This fundamental investigation of non-contact EFs in laser processing puts forward an approach that enables control over fluid responses independently of laser parameters.