Multiphysics modeling of thermocapillary force driven pore elimination from liquid metal droplets for manufacturing pore-free powders for additive manufacturing

Abstract

Gas atomization (GA) is a widely adopted method for metal powder production, involving the atomization of molten metal using pressurized gases. Despite its prevalence in additive manufacturing (AM), GA-produced powders often contain pores that can transfer to the as-built parts to deteriorate part quality. Here, we report an approach to achieve pore-free gas-atomized metal powders by inducing a reversed thermal gradient through rapid heating. The resultant thermocapillary force drives the pores out of the molten metal droplets. We demonstrate the feasibility of utilizing rapid heating to eliminate pores from droplets of different metal alloys, using high-fidelity simulation. Furthermore, we derive an analytical model to estimate the critical thermal gradient needed for pore-free powder production.